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Russian
00:00:01
dearest python programmer welcome00:00:04
to my channel where I teach you00:00:06
programming languages in a00:00:07
practical, fast and fun way00:00:10
I am very happy to present to you today00:00:11
this fabulous complete python course00:00:14
for beginners if you have never written00:00:16
programming code before Now00:00:18
and you want to learn to program00:00:20
from scratch this video is perfect for you00:00:23
or if you already have some experience and00:00:25
want a course that00:00:27
clearly illustrates all the fundamental topics00:00:29
of the Python language, a course that you can then00:00:31
consult whenever you need00:00:33
to information on a given topic well00:00:35
this is the right video python and00:00:38
my absolute favorite language is00:00:40
an extremely simple language00:00:42
therefore it is the best language to00:00:44
learn for those who have never programmed00:00:45
and are starting from scratch at the same time it is a00:00:48
very powerful language that it allows you to00:00:51
create apps for smartphones00:00:53
artificial intelligence software machine00:00:54
learning video games websites and much00:00:57
more, it is no coincidence that it is one of the most00:00:59
popular languages at the moment and is widely used by00:01:02
companies such as google00:01:03
instagram huber spotify netflix and many00:01:07
others so if you are looking for a job it is the00:01:09
right language for you in this video00:01:11
we will learn together all the00:01:13
fundamental elements of python and we will use them to00:01:16
create a beautiful up step by step00:01:19
the up will consist of a00:01:22
virtual assistant who will welcome customers in one of00:01:25
our hypothetical imaginary bars00:01:27
offering them very fresh drinks00:01:29
at the end of this video you will be able00:01:31
to read and understand00:01:34
programming code like this and00:01:35
write it with your own hands to create00:01:38
fantastic apps with the most disparate uses.00:01:41
During the course I will also assign a00:01:42
small exercise to solve to00:01:44
test the notions that you have00:01:46
learned well. now without further ado let00:01:48
's start this beautiful00:01:50
Python learning experience together it doesn't matter00:01:53
if you are big or small I could write00:01:55
your first Python program in00:01:57
literally a few seconds now let's start00:01:59
immediately and while the acronym is scrolling click00:02:02
the subscribe button also activating the00:02:04
bell00:02:05
don't get lost in the next00:02:06
educational and fun videos on the wonderful00:02:09
world of programming00:02:11
[Music]00:02:17
well before we start programming in00:02:20
python we have to download it and00:02:22
install it on our PC if you already have00:02:24
python installed I can skip this00:02:26
part and go directly to the00:02:28
next chapter you can find the list of chapters00:02:30
here under the video in the description box00:02:32
very well to download00:02:34
python let's go to the python dot org00:02:36
slash download site if you want you can find00:02:39
this link it's always down in the description00:02:41
let's click here on this nice00:02:43
yellow download bison button don't worry00:02:46
if you see a00:02:47
slightly different version code because python is00:02:49
constantly updated00:02:50
once the download is complete we have the00:02:52
installation file which you will find in the00:02:54
download folder or directly here00:02:57
on the browser make sure to check00:02:59
this box and press stop00:03:01
now at the end of the installation00:03:03
we open the python development environment00:03:06
which is called hydro integrated00:03:08
development and learning environment00:03:10
let's take the windows key on the00:03:12
keyboard and write aido here we go00:03:14
let's open it excellent this is the so-called00:03:16
pato shell and here in the shell we00:03:19
will see our program in action00:03:21
but first we have to write our program00:03:24
let's go to file and we choose00:03:26
new file and in this window00:03:29
we will write the lines of code that will00:03:31
make up our program to00:03:33
work better we can modify00:03:34
the window aesthetically I go to00:03:37
option configure idol and increase the00:03:39
size of the text press fly here it is00:03:41
much better it is less tiring00:03:44
eyes I advise you to go to00:03:45
highlights and choose the dark theme00:03:47
I press apply very well now I'm really at00:03:51
ease excellent now we are ready to give00:03:53
life to our first program in this00:03:56
window as I told you we can00:03:57
write the commands the program must00:03:59
execute as we said at the beginning of00:04:01
the video we will create an app together for00:04:04
our imaginary pub which we will call00:04:07
pub drink and code yes I like it the most00:04:10
will consist of a friendly00:04:12
virtual bartender who will welcome customers and00:04:14
offer them excellent drinks I already imagine00:04:17
a screen at the entrance of the pub where the00:04:19
customers will use the app to order a00:04:21
nice mojito or a lemonade becky00:04:24
we are waiting for us right away but the first thing00:04:27
our app must do is print00:04:29
a nice welcome message for the00:04:31
customer no but how do you print a00:04:34
message on the screen it is very simple00:04:36
we use a function called print which00:04:40
in English means to print look at00:04:42
the development environment it has recognized00:04:44
the function I wrote it is colored00:04:46
in purple all the functions are00:04:48
represented in purple and are always00:04:50
followed by round brackets inside00:04:54
the round brackets we insert what00:04:56
we want to print on the screen well we want to00:04:58
print a welcome text for00:05:01
example welcome to the pub drink and codes00:05:04
the text or a set of letters00:05:06
other characters in the world of00:05:08
programming it is called a string and must be00:05:10
inserted between single or double quotes here00:05:13
is the development environment recognizes00:05:15
that this is a text string and I00:05:17
color it green my favorite color00:05:20
well now we have a print function that00:05:22
will print a string but as we have00:05:26
our app to see if it works it is00:05:28
very simple we press the f5 key00:05:30
on the keyboard or let's go up here to00:05:34
run and press run module we will be00:05:36
asked to save the file I have saved it00:05:38
on the desktop with the name virtual barista00:05:41
let's save it and it works the app has been00:05:44
run and has printed00:05:46
the welcome message on the screen here on the shell00:05:48
maybe he is having second thoughts that this00:05:50
interface is not very00:05:52
aesthetically pleasing is that a customer who00:05:54
used this app of ours would not00:05:56
particularly appreciate the graphics00:05:58
but don't worry with python it is00:06:00
possible to create beautiful00:06:02
graphic interfaces and even00:06:04
video games on my channel I have published00:06:06
several videos on these topics but00:06:08
they are a slightly more00:06:10
advanced level so for now we continue00:06:12
to learn the basic concepts well00:06:14
now under this message out of00:06:16
print other messages in which00:06:19
our virtual barman introduces himself and00:06:21
welcomes the customer but how do we print00:06:23
other messages one after the other00:06:26
very easy let's go back to the virtual barista file00:06:28
and add a new00:06:30
print function with a new string my00:06:33
name is edo bot feel free to give00:06:36
the barista the name you prefer and in00:06:38
another print and I'm ready to serve you00:06:41
with a nice smiley the instructions in the00:06:43
languages of programming are00:06:45
executed in order from top to00:06:47
bottom so these three strings00:06:50
will be printed one after the other00:06:52
we have the program again by pressing00:06:54
f5 if it asks you to save accept and00:06:57
voilà the messages are printed one00:06:59
after the other I can already imagine the expression00:07:02
on the faces of our customers when00:07:03
they are welcomed by edo pot now that the00:07:06
customer has been welcomed by the pub let's get00:07:08
to the point00:07:09
we want to present to the customer the drinks00:07:11
available in our cellar and00:07:13
their price in reality we would have a00:07:15
real cellar with various boxes00:07:17
where they are stored drinks and other00:07:20
similar products in the off we will therefore have to00:07:22
recreate a virtual cellar instead of00:07:25
real boxes there will be00:07:28
virtual boxes or memory areas00:07:30
where to store the available drinks,00:07:32
prices and other useful data but how do you00:07:35
create memory areas for00:07:37
to preserve useful data they are created with00:07:40
variables variables are a00:07:43
fundamental element of programming which I will00:07:45
explain to you straight away to explain them create00:07:48
a new file for a moment by going to file and00:07:50
new file and saving it immediately with fi00:07:53
save as calling it explanations why00:07:56
in this file I will explain the00:07:58
programming notions to you and then once00:08:01
explained we will apply them to our00:08:03
virtual bartender app. Very well let's imagine that00:08:06
in the cellar of our pub we have a00:08:09
special drink much loved by customers00:08:11
called digital vodka. I want to00:08:15
keep it in the memory of our00:08:17
program so I create a variable that00:08:20
it's called a special drink and its value00:08:22
is the same as digital vodka, that's it, it's00:08:27
simple, no, I created a memory area00:08:29
called a special drink that contains a00:08:32
string, digital vodka, imagine00:08:35
a box with a label on which00:08:37
Trent Special is written, which contains at00:08:39
its inside a text digital vodka if00:08:42
we follow this program with f500:08:45
no message is printed on the screen00:08:47
well it is normal after all we have not00:08:49
inserted any print function and it is00:08:52
only the print that can print messages00:08:54
on the screen but even on the screen00:08:56
we do not see anything the command was00:08:58
executed and the variable has been created I00:09:00
will demonstrate it to you immediately here on the shell00:09:02
I can see the stored variables00:09:05
just write the name special drink00:09:07
first send pan here is the value digital00:09:11
vodka but I can also print the00:09:12
variable with a simple print go back00:09:15
to the file I write print and all inside00:09:17
I insert the name of the variable the00:09:20
program reads the value of the00:09:22
variable which is the string digital vodka00:09:24
and will insert this string inside00:09:27
the print it is as if the variable were00:09:29
a package and the string was the00:09:31
gift inside the program will then00:09:33
break this variable revealing the00:09:36
string inside I start with f500:09:39
here it is digital vodka attention let's go back to the00:09:43
file the name of the variable must not be00:09:45
written between apc like this because by doing so00:09:48
we will not be printing the special tring variable we00:09:51
will be printing a00:09:54
text string with special drink written which it00:09:57
has nothing to do with the variable let's00:09:59
start the program here you see so be00:10:02
careful the strings go between apx and00:10:05
are green in color the variables instead00:10:07
are neutral in color and have no friends00:10:10
here let's eliminate storing a00:10:12
string inside a variable it's00:10:14
fine it's exactly that that we have00:10:16
done here we can also modify the00:10:18
value of a variable if we have00:10:20
invented a new recipe for00:10:22
our special drink and instead of00:10:24
vodka we use whiskey we rewrite00:10:27
special drink but this time we call it00:10:29
technical whiskey we print the00:10:32
variable on the screen again and before starting00:10:34
the program remembers the code is00:10:37
executed from top to bottom therefore00:10:40
first the variable is created and00:10:42
assigned the string digital vodka00:10:44
then it is printed on the screen immediately after00:10:47
the variable is assigned a new00:10:49
value techno whiskey overwriting00:10:52
the previous one00:10:54
finally it is printed on the screen these00:10:56
two tips are precisely what we will see on the00:10:58
screen in fact the program starts00:11:01
here is digital vodka and then techno00:11:04
whiskey be careful the variables exist00:11:07
and maintain the assigned values only00:11:09
during the execution of the program00:11:11
when the program is terminated or00:11:13
restarted the variables disappear and00:11:16
the data saved in they are lost00:11:18
excellent let's go back to the code00:11:20
let's summarize to create a variable00:11:23
where to store useful data I write the00:11:26
name of the variable I put the00:11:28
equal sign and insert the much desired00:11:30
in this case a witch I don't necessarily have to00:11:33
insert a witch00:11:36
in fact there are other types of data that can00:11:38
assign a number to a variable for00:11:41
example I'll show you let's delete for a00:11:43
moment and suppose that it's in the cellar00:11:45
we have a large stock of00:11:47
special drinks for example 28 portions create a00:11:51
new variable called quantity of00:11:53
special drink and assign it the number 28 let's00:11:56
print the variable with a nice00:11:58
print let's start the program here it is 2800:12:02
as you can see the numbers should not be enclosed00:12:05
in quotes if I insert the quotes so00:12:07
this will no longer be a numerical data00:12:10
but a witch and we will see00:12:13
later the problems that could arise again00:12:15
let's remove the quotes very well this in00:12:18
particular data is of the inter type, i.e.00:12:21
an integer number, but I can also insert00:12:24
numbers with a comma or00:12:27
flat type. I can need a number with a00:12:29
comma to memorize the price of a00:12:31
drink. Let's delete, write the price of the drink00:12:35
equal to 5 euros and 50 cents. Let's print and00:12:38
start. et voilà, in addition to the00:12:41
integer and flop string variables,00:12:44
there is also the pool and we delete00:12:47
the boolean it can have two values or00:12:50
through or falls that is true or false for00:12:53
example which is a variable that00:12:55
tells you epub is open to the public I write00:12:58
pub open equal through true if the pub00:13:02
is open or I write falls if the pub00:13:05
is not open maybe it is closed for holidays or00:13:07
bankruptcy let's hope not let's print00:13:11
to print start with f5 that's it false00:13:15
excellent now that we have learned to use00:13:17
variables to store00:13:19
useful data let's use them immediately in our app00:13:22
let's delete everything here ok and go back to the00:13:25
virtual barista file the variables00:13:27
usually declare at the beginning00:13:30
of the program let's insert the00:13:32
special drink to offer to the customer00:13:34
special dream equals digital vodka and00:13:37
also insert its price00:13:38
drink price equals 5 euros and 50 we00:13:42
also learned how to print00:13:44
the variables on the screen we proceed immediately after the00:13:46
edo bot introduces itself we want it to say the00:13:49
coolest drink in our pub is and immediately00:13:52
after we write print drink special we00:13:55
have our asp and let's see what00:13:57
happens fantastic after the usual00:13:59
presentations00:14:02
the most closed drink is printed on the screen, our father is00:14:04
digital vodka, let's go back to the code and00:14:06
also present the print price,00:14:09
try it immediately at the modest price of the print00:14:12
drink price and let's start again,00:14:15
here we are, our virtual barman is00:14:17
doing a really excellent job00:14:18
talking to customers00:14:20
now, however, customers must also be able to00:14:23
reply to him to choose which trinkets00:14:25
to purchase or enter their data such as00:14:27
name, surname, date of birth, so far however00:14:30
the user can read the messages on the00:14:33
screen but how can we ensure that he00:14:34
can write to enter data and00:14:37
information and carry out choices00:14:40
I'll explain it to you straight away00:14:41
let's go back to the explanations file you've learned00:14:43
well that the program can send00:14:45
readable output on the screen using the00:14:48
print function if I write print and00:14:50
giacomino and start the program here I go I read00:14:53
giacomino on the screen but if I were00:14:55
a customer who wants to send an input to the00:14:59
program for example write my00:15:01
name instead of a print and we delete00:15:04
I write a very simple info for this00:15:07
function it is not even necessary00:15:09
to insert it is stuff in round brackets if I00:15:12
now start the program magic a00:15:15
flashing cursor appears and I can write00:15:17
words numbers special characters00:15:19
any value you want let's say it is00:15:22
the input function works in the00:15:24
same way and a place for print the print00:15:28
takes a string from the program and gives it00:15:30
to the screen the input takes a string00:15:33
from the screen and from the program to00:15:36
send this beautiful string to the00:15:37
program I press enter but now the00:15:40
program ends because we go to the00:15:42
code the input is alone and the00:15:46
string value that it takes from the screen00:15:47
is lost because it is not saved00:15:50
anywhere but we have learned how to00:15:53
save values in the program no00:15:55
of course yes with the variables00:15:58
so let's go here and we write00:16:00
inserted string equals input function in this00:16:04
way the string inserted on the screen00:16:06
by the user will come out of the input and00:16:09
will be immediately saved in a variable00:16:12
so it will not be lost and we can00:16:14
reuse it. In computer language it is00:16:16
said that a function returns a00:16:19
value for example the input function00:16:21
returns a string written on the screen00:16:24
by the user now that we have saved the00:16:26
string inserted in a variable we00:16:28
print the screen to see if it is00:16:30
correct as usual I write print00:16:32
the name of the00:16:34
variable whose value I want to read is in round brackets00:16:36
we have for see if it works00:16:38
away here the indicator appears and I can00:16:41
write something perfect the string00:16:44
is saved correctly and then00:16:46
shown on the screen it's exactly what00:16:48
I wrote fantastic with this00:16:50
knowledge we can already talk to the00:16:52
customer in our app ask00:16:55
questions and get answers00:16:56
Let's clean everything here, here's the00:16:59
important hygiene and let's go back to the00:17:01
virtual bartender after the small advertisement for the00:17:04
drink recommended by the house. We'll ask00:17:06
the customer what your name is. We'll create a00:17:09
customer name variable where we can store00:17:12
the name written on the screen by the customer,00:17:14
which will be returned from the input and now let's00:17:17
create a personalized message for00:17:19
the customer we write welcome dear00:17:22
and we print the customer's name before00:17:25
starting the program we00:17:26
also ask him for his date of birth00:17:28
we need to know it because in our pack00:17:31
we will also take alcoholic drinks and00:17:34
we don't want to incur penalties for00:17:36
selling to minors we do00:17:38
exactly that the same thing I write a00:17:40
question in which year you were born except in the00:17:43
variable they have birth the year that will be00:17:45
inserted by the customer and then I reply00:17:48
senate in the print year of birth00:17:52
everything seems fine let's see if it works away00:17:55
fantastic after the printouts seen00:17:57
previously our good barman00:17:59
asks what is your name I can write00:18:03
giacomino welcome dear giacomino00:18:06
perfect and now in what time you were born in00:18:09
2010 at the top in 2010 excellent now00:18:13
we have to calculate the age of the customer00:18:15
because be careful if a customer was born00:18:19
in 2010 and we are in 202100:18:22
it means that the customer at 11 years of age and by00:18:25
current legislation we cannot sell00:18:27
alcohol to a minor, only00:18:29
non-alcoholic ones but how can we do00:18:32
mathematical calculations in the program not00:18:35
only to calculate the age of a customer00:18:37
also to take into account the trinch00:18:39
purchased and sold to apply00:18:41
loyalty discounts etc. let's move on in the00:18:44
explanation file that I will explain to you00:18:45
straight away, let's imagine that in our00:18:47
pack we have 5 different drinks from which the00:18:50
customer can choose, they are just a few, well come on,00:18:53
we have just opened the pub, later on00:18:55
the customers will have more choice but for now00:18:57
the drinks available are five bands00:19:00
let's write it available drinks equals 500:19:03
let's suppose that three of them are00:19:05
alcoholic and 2 non-alcoholic then instead of00:19:09
a number we can write a00:19:11
mathematical operation 3 plus 2 let's print00:19:15
the variable here and start00:19:18
the operation well three plus two returns an00:19:20
integer number 5 which is saved in the00:19:23
variable and then printed the plus symbol00:19:26
is called operator to be precise00:19:29
binary operator because it makes a calculation00:19:31
between two numbers there are many other00:19:34
binary operators the main ones are plus00:19:37
or minus x and divided as well as doing00:19:40
calculations with simple numbers we can00:19:42
also do calculations with variables that00:19:44
contain numbers let's delete and see00:19:47
an example we said that there00:19:49
are three alcoholic drinks, so there00:19:52
are two non-alcoholic drinks so the00:19:55
available drinks are equal to the sum of the00:19:58
alcoholic drinks plus the non-alcoholic ones so we are00:20:00
adding the values contained in the two00:20:03
variables also in this case the00:20:05
program will take care of unpacking the00:20:07
two variables, read the value00:20:09
contained within them and00:20:11
insert it here so the00:20:12
mathematical operation can be carried out and the00:20:15
resulting value saved in the00:20:17
drink variable available if we print00:20:19
the result and we have00:20:22
always had 5 the calculation is correct, in addition to the00:20:25
binary operators00:20:27
we also have the one ri operators they are00:20:29
very useful I'll show you we delete00:20:31
I declare the variable available drinks00:20:34
equal to 5 and the print now let's imagine we00:20:38
have invented two new very fresh00:20:40
drinks I write available drinks plus00:20:43
equals 2 to increase of 2 the value00:20:46
of the variable if we print we have00:20:50
perfect the available drinks are now 700:20:53
there are many other operators one ri the00:20:56
main ones are the addition to the00:20:57
subtraction is the multiplication and00:21:00
division as well as with the integer numbers00:21:02
int we can also do operations here are00:21:05
the numbers with the comma flot we delete00:21:07
and write the price of a drink00:21:09
equal drink price is 4 euros and 25 cents the00:21:13
most loyal customers can access a00:21:15
loyalty discount equal to one euro and00:21:18
fifty then the discounted price is00:21:21
equal to the drink price less loyalty discount00:21:24
we print the discounted price00:21:27
let's start here the nicest customers00:21:30
pay only 2 euros 75 let's go that the00:21:34
operations we can also insert00:21:35
directly into the print or other00:21:38
functions instead of defining the00:21:41
discounted price variable and writing this print we00:21:43
delete them we can more quickly00:21:45
write rint drink price less00:21:49
loyalty discount also in this case the00:21:51
program will take care of unpacking the00:21:53
two variables by inserting the relative00:21:55
values. We start the program and00:21:58
the result is the same because it calculates00:22:00
the result of the subtraction on the fly and then00:22:02
prints it on the screen. In this way the00:22:05
shorter code but the result of00:22:07
this association is not stored00:22:10
on any variable so once the00:22:12
screen is printed it is lost if we want to00:22:14
reuse it in the future without having to00:22:16
redo the subtraction every time it is00:22:18
better to save it on a variable well let's00:22:21
delete and continue remember the00:22:23
Boolean variables for example00:22:26
pub open equals through exist00:22:28
una ri operators also for Booleans and00:22:31
they are called logical operators but00:22:34
we will talk about them later when we study00:22:36
Boolean logic we cancel finally00:22:39
there is an operator also for00:22:41
strings I'll show it we pull a00:22:43
variable of type string name barman00:22:46
equals edo bot we print we have00:22:49
excellent and I have bot now this nice00:22:53
name is made up of edo plus bot we can00:22:57
just write like this string is do you00:23:00
string bot that's it if we have the00:23:04
result it will be the same well this plus00:23:07
two strings is called the concatenation operator00:23:10
and as you have just seen it00:23:12
produces a string result that it is given00:23:15
by the union of the two00:23:17
original strings, even the00:23:19
concatenation operator, like the operators seen00:23:21
previously, can be inserted00:23:23
directly into a print00:23:25
to print messages made up of multiple00:23:28
strings, for example writing hello00:23:30
my name is more edo bot we have it here it is00:23:35
or given that the edo bot string is already00:23:38
contained in the barman name variable it00:23:40
would be even better to write hello I00:23:43
love the more barman name we have and voilà the00:23:47
result is the same00:23:49
let's go back to the code and00:23:51
pay attention the concatenation operator00:23:54
was presented with a plus symbol but00:23:57
as you will have intuition works in a00:23:59
totally different way from the sum operator00:24:02
seen previously the00:24:04
concatenation operator joins two strings00:24:06
instead the sum operator makes a00:24:09
mathematical diction between numbers whether they are of type00:24:12
in a flop00:24:14
do not confuse the two operators00:24:15
even if both are represented with00:24:18
one more I'll show you a very00:24:20
common error let's delete a little let's create an00:24:22
int type variable therefore an integer number00:24:26
now I'll create another string type variable don't00:24:29
be fooled by the fact that00:24:31
a 2 is written in the string the program00:24:34
doesn't see it as an integer but00:24:35
like a written text string00:24:38
because it is enclosed in apc in fact00:24:41
the development environment colors it in00:24:43
green while integer numbers or flops are00:24:47
colored in white now you don't feel an00:24:51
unhealthy irrepressible desire to add00:24:53
a number with a string to see what00:24:56
happens I'll tell you what happens00:24:58
the apocalypse00:25:01
no come on nothing that serious what00:25:03
happens is called an exception let's try00:25:06
together to find out what it is I'll00:25:08
try to write c equals plus p ready for00:25:12
the explosion let's start the program00:25:14
here it is the writing that we see in red00:25:17
is an exception in practice an00:25:20
error has occurred in the program00:25:22
the line of code that00:25:24
generated the error is highlighted as we expected it is00:25:26
indeed her ci equals to plus b the error is00:25:29
classified as type error00:25:33
type error and a brief description is also given00:25:36
the types of the operands00:25:38
are not supported for the plus symbol00:25:40
because we are trying to add 1 int00:25:44
with a string the variable b we are00:25:47
basically adding a number with a00:25:49
word it doesn't make any sense00:25:51
what we can do no it is convert00:25:54
the string into an integer let's go back00:25:56
to the code look what I do I enclose00:25:59
the string variable inside the int00:26:02
function the int function is capable of00:26:05
converting integers the00:26:08
compatible string type variables the00:26:10
int function will therefore take the 2 of type string00:26:14
and it will return a 2 of type int which will be00:26:17
immediately added without any00:26:19
error with the other variable itself00:26:21
we print we start wonderful no00:26:25
exceptions and the result is equal to 5 as00:26:28
we are imagining beyond the00:26:30
int conversion function00:26:32
there is a function for each of the00:26:34
data types that I taught you00:26:36
boolean slot and string and regarding the00:26:39
string function let's do an experiment00:26:41
instead of converting the00:26:43
string variable into an integer let's try to convert00:26:46
the integer variable into a string and see00:26:49
what happens we can do it thanks to the00:26:52
string function str we have look this00:26:56
time the result is the string 3200:26:58
this is because now we have two strings and00:27:01
the plus symbol between two strings00:27:04
always escapes from concatenation not from00:27:06
mathematical addition therefore00:27:09
we do not obtain a number 5 but a string 3200:27:11
formed by the concatenation of the00:27:14
strings 3 and 2 very well now that we have00:27:17
learned all this new knowledge and00:27:19
it's time to apply it to our00:27:21
amazing up, let00:27:22
's start by making the code a little more00:27:24
tidy and organized, add00:27:27
a barman name variable at the beginning with the00:27:29
value edo bozzo and now let's merge these00:27:32
two prints into a single one with the00:27:34
print concatenation operator my name is more name00:27:39
barman view and I am ready to serve you00:27:42
well so the message will be printed00:27:44
all in the same line00:27:47
also using the variable name barman00:27:49
let's try to start here it is perfect00:27:52
let's do the same thing with the other00:27:54
messages the drink more cool of our00:27:56
pub is more and now we insert the variable00:28:00
in special drink taking care to00:28:02
convert them into string thanks to the00:28:05
function we have learned we do00:28:07
similarly for the following print00:28:09
this time the variable and flop we convert00:28:11
the always into string to concatenate the00:28:14
without errors let's try to start00:28:16
beauty the program is always00:28:18
nicer now let's add comments to the code00:28:21
the comments are sentences that00:28:24
we can insert to explain in words00:28:26
the different instructions of the code they are00:28:29
very important when working in a00:28:31
team because if we pass the code it is one of00:28:33
our colleagues and it could be find it difficult00:28:35
to understand it or even ourselves in00:28:38
a few months we may forget the00:28:40
meanings of certain instructions and00:28:42
why we used them now00:28:44
our app is very simple for now00:28:46
but it is always good to add a few00:28:48
short comments to add a00:28:50
comment we write pound sign or hashtag00:28:53
that if you prefer, this symbol is used00:28:55
to tell the program to00:28:57
completely ignore what we are going to00:28:58
write because it will in fact be00:29:01
a comment, an explanation in words that is00:29:03
only useful to us humans to understand the00:29:05
code, the development environment recognizes00:29:08
the symbol and highlights it red00:29:10
thank you very much let's write00:29:12
variable declaration for example because in this00:29:14
section of the code we are actually00:29:16
declaring the variables that we00:29:18
will then need before the first00:29:20
function let's write start of the program00:29:22
because it is from here onwards that the00:29:25
substance begins the comments are useful and00:29:27
advantageous if not they are used00:29:29
excessively, every single instruction began to be commented on,00:29:32
even the most banal ones,00:29:34
with irrelevant comments. I'm just00:29:37
polluting and making the code heavier00:29:39
instead of making it understandable,00:29:41
so I don't invite you to add a00:29:43
comment for each of these fakes, for00:29:45
example because they are already clear. and00:29:47
understandable in themselves well after this00:29:49
brief digression on the comments00:29:50
let's proceed with the code let's delete00:29:53
all these instructions which are now a00:29:55
bit too many and insert only the00:29:57
most important request insert00:29:59
your year of birth this character00:30:01
back slash n which made the string not00:30:04
it's a typo,00:30:06
it's a special character in the strings00:30:07
that is used to wrap the line, in fact you00:30:10
start the program and00:30:12
here the string wraps immediately00:30:13
because it starts with the special character and00:30:16
then continues with the text so a00:30:18
nice space is created that separates the messages00:30:20
introductory from the questions that we are going to00:30:22
ask the customer00:30:24
now we give the customer the right to00:30:26
respond by entering his year of00:30:28
birth00:30:29
I write year of birth equals input the00:30:32
input as you will remember returns a00:30:35
string but we want their00:30:37
birth to be an int number so no00:30:40
errors will occur when we will calculate00:30:42
the age of the customer then I convert on the00:30:44
fly the value returned from the input00:30:46
by closing it inside the function in00:30:49
perfect now I can use it to calculate00:30:52
the years of the customer I write customer years00:30:55
equal to 2021 which have the current one minus00:30:59
the customer's year of birth00:31:01
now we can print on the screen and the00:31:03
customer's age by writing print to the most00:31:07
customer years converted on the fly into a string00:31:09
because basically it is an integer you years00:31:12
let's see if it works 3 2 1st go well00:31:17
after the insertion request I can00:31:18
insert 2005 for example first sending to00:31:22
16 years old magnificent it works very well00:31:25
now we ask for calculated age I want to00:31:27
offer the customer some drinks but00:31:30
always keeping in mind if he is an adult I00:31:32
will explain myself better if the customer is an adult I00:31:35
offer you alcoholic and non-alcoholic drinks00:31:38
by printing them on the screen with a print00:31:40
otherwise he is a minor I print with a00:31:44
print only soft drinks00:31:47
but how can I execute a print or other00:31:49
instructions only if a00:31:52
condition decided by me is respected it is very simple let00:31:55
's move on to the explanations file and let's see them00:31:57
together let's imagine we have a00:31:59
variable where the age of the customer is stored00:32:01
customer years equal to 1600:32:04
example well I want the00:32:07
screen to be printed with the print the sentence if a00:32:09
minor to order only alcohol but00:32:12
only if the customer painter ter or if the00:32:15
customer is under 18 years old well let's00:32:18
write just this if the customer00:32:22
is under 18 years old in English if you say the00:32:26
ladies and gentlemen here is the00:32:28
declaration iv as you can see it is very00:32:31
readable we are writing almost00:32:34
with real words the requirement00:32:36
that interests us now let's write a colon we00:32:39
press enter to go to the beginning and00:32:42
we write the desired message well00:32:44
I would have noticed that when I pressed enter00:32:47
to go to new line00:32:49
a sort of space automatically appeared00:32:52
this space is called indentation00:32:54
don't worry now I'll explain everything00:32:57
the iv declaration is used to00:33:00
execute one or more instructions if and only00:33:03
if a condition is true it is made up00:33:07
of the keyword iv colored in00:33:09
orange and from the condition to be00:33:12
respected followed by the two you all00:33:14
have the indentation and finally00:33:17
the instruction to execute if this00:33:18
condition is true now customer years is00:33:21
equal to 16 therefore it is true that it is less than00:33:24
18 therefore this print will be executed00:33:27
let's start the program and00:33:29
very well the message has been printed00:33:32
if I go back to the code I change the customer years value00:33:34
to 23 for example this00:33:37
condition will no longer be true so00:33:40
the dead silence program is executed the00:33:42
message is no longer printed as00:33:45
you can see the declaration iv is extremely00:33:47
useful and offers us many other possibilities00:33:50
let's go back to the code in the condition I00:33:52
used the smaller symbol this is called the00:33:55
comparison operator and there are00:33:59
many others we have the smaller equal the00:34:02
greater the greater equal the double00:34:04
equal which would check andi customer has a00:34:06
value equal to 18 be careful to use00:34:10
the equal single this is an00:34:12
assignment operator that is used to assign00:34:15
a value to the variable as we have00:34:17
done here it is double equals that is used to00:34:20
check if the variable is equal to00:34:23
a value we can also check if00:34:25
the variable is different from a value00:34:27
using equal exclamation point all00:34:30
the comparison operators just00:34:32
seen compare two green les and00:34:35
return a true or false boolean value.00:34:39
this value is used by the list to00:34:40
decide whether or not to execute the00:34:43
invented instruction and by the way, if you accidentally delete00:34:46
the indentation you can insert it00:34:48
with the tab key on the keyboard if after the00:34:51
inserted instructions I go to the end with the00:34:53
enter key I can insert other00:34:55
instructions to execute if the condition00:34:57
is true always maintaining the intention but00:35:00
for now not to episodes of other00:35:02
instructions we delete and repeat00:35:04
the operator that interests us less00:35:07
in summary we are printing six00:35:09
minor if the customer is under00:35:11
18 but if he is over 18 I00:35:14
want to escape you are an adult how00:35:17
can I do00:35:18
well it's very simple after the00:35:20
declaration iv I add els which in00:35:23
English otherwise means two dots00:35:26
send and here always with indent00:35:29
I write if you are an adult you can order00:35:32
alcoholic and non-alcoholic00:35:34
simple no in the hit we write the00:35:37
instructions to execute if the condition00:35:38
is true in the els we write the ones to00:35:41
execute if the condition is false the00:35:43
hell's is optional we can add it00:35:46
only if we need it let's try to00:35:48
start the code now customer years is00:35:50
even at 23 so the condition of the iv00:35:53
is false therefore this print will not be00:35:56
executed but the one00:35:58
inside the els declaration will be executed00:36:01
we have it's00:36:02
fantastic it works you are an adult you can00:36:05
order alcoholic and non-alcoholic drinks a it's00:36:08
nice to be adults beyond hell's00:36:11
I can also add the declaration00:36:13
el ict the elif is executed if the00:36:16
condition of the iv and force but if00:36:19
another condition specified by us is00:36:22
true it is very useful let me explain immediately00:36:25
if the customer is under 18 years old I print00:36:27
followed00:36:28
otherwise if the customer is over 8000:36:31
years old00:36:32
I want to run away then he will order alcohol but00:36:34
take it easy no no if now the customer is 8500:36:38
years old and I start the program here00:36:40
comes our rather00:36:42
unpleasant phrase I can insert how many helixes00:36:45
I want one after the other00:36:46
always after the iv but before the hell's00:36:49
if present if we have an else at the00:36:51
end as in this case it will be00:36:54
executed if the condition of the iv and the00:36:56
conditions of all the others is leaf are00:36:59
false for example if the customer has00:37:01
an age that is not less than 18 and is not00:37:04
even greater than 80 for example 4500:37:08
years the hell's instruction will be executed I00:37:10
start the program and voilà well as well as00:37:13
with pink or float numbers00:37:16
we can use it iv declaration also00:37:18
with strings we delete everything and00:37:20
write the name of the customer who is00:37:23
using our app customer name00:37:25
equals piergiorgio for example if00:37:29
customer name is equivalent to giacomino our00:37:32
favorite customer I want to print00:37:34
hello giacomino on the screen and nice00:37:36
to see you again with a nice little heart if00:37:39
we start the program now no message will be00:37:41
printed because the00:37:44
customer name is not equal to giacomino if00:37:47
I replace the customer name with00:37:48
giacomino the condition will be true00:37:51
we have and here is our very00:37:53
affectionate excellent message we00:37:56
used the iv declaration with the numbers with00:37:59
the strings and now all that remains is to use it00:38:01
with the booleans let's delete everything and create00:38:04
a boolean variable open pub equal00:38:07
through we can serve drinks it is00:38:09
only if the our pub is open00:38:11
obviously then I write iv pub open00:38:15
it is true print screen we are ready00:38:19
to serve you with boolean variables00:38:21
I can also write only iv pub00:38:24
open the result will be the same and00:38:26
so the condition is even more00:38:29
readable if the pub is open00:38:32
we are ready to serve you if we have the00:38:35
message it will be printed if I go back to the00:38:37
code and enter falls restarting we will not00:38:40
see any perfect message now00:38:43
let's imagine making a00:38:45
home delivery service available for00:38:48
our customers I will want to print we are00:38:50
ready to serve you if the pub is open00:38:53
or if the home delivery is00:38:55
active for those who also in this case00:38:57
we could serve the customer but how00:38:59
can I do this is very easy with the00:39:02
operators in Boolean logic create a00:39:05
new variable active home delivery00:39:07
equals through or abbreviated a little00:39:09
otherwise the name is too long now I can00:39:12
modify life by writing if pub is open00:39:15
or home delivery and activates00:39:18
the horror operator is a00:39:20
Boolean operator that checks the two variables00:39:23
and returns through if at least one00:39:26
of the two is true there is also00:39:28
the end operator that returns through00:39:30
only if both variables are true00:39:33
finally we have the north operator which00:39:35
is used to invert the boolean value of00:39:38
a variable of the variable through00:39:40
will return falls if the variable falls00:39:42
will return troupe for example let's delete00:39:44
the condition for a moment I can write00:39:46
if I notice the pub is closed i.e. if the pub is not00:39:51
closed print we are ready to serve you if00:39:54
the variable with value through so it is00:39:56
true that the pub is closed at night00:39:58
will return falls to the into function00:40:01
so the message will not be printed00:40:03
and it is correct because it is yes oh well closed we do00:40:06
n't want to escape we are ready for00:40:08
services we can only use more00:40:10
Boolean operators together to create00:40:12
complex conditions for example if the pub is not00:40:15
closed or home delivery is00:40:18
active and the drinks are not finished00:40:21
we can serve the customers this00:40:24
condition is quite complex the00:40:26
Boolean logic offers a lot of00:40:28
possibilities but it is always good practice00:40:30
to create short and understandable conditions00:40:33
excellent now that we have acquired a lot of00:40:35
excellent notions we can continue00:40:37
our app00:40:38
so let's go to virtual bartender and after00:40:40
calculating the age of the customer00:40:43
we want to offer him alcohol00:40:44
only if he is of age00:40:46
then I write a hit years customer is00:40:49
under 18 print you are a minor you can00:40:53
only order non-alcoholic drinks otherwise you are an00:40:56
adult you can order alcoholic and00:40:58
non-alcoholic drinks I put a nice new00:41:01
line character in both to make some00:41:03
space from the previous messages or a nice00:41:05
f5 to start the program and enter00:41:08
your year of birth 2000 at the age of 2100:41:11
you are an adult excellent evenings via the00:41:14
program and I write 2005 at the age of 16 you are00:41:18
a minor well it works perfectly00:41:20
well guys we have already learned a lot00:41:22
of python knowledge and we will learn many00:41:25
others it is extremely useful during the00:41:27
video so now is the time just to00:41:29
give you a good exercise it will be short00:41:32
but it will contain all the notions acquired so far00:41:34
so I could put them into practice and00:41:37
consolidate it if you are finding the video00:41:39
interesting leave me a nice like it is00:41:40
really appreciated and write to me in a00:41:43
comment why you decided to learn00:41:45
Python I'm really curious to00:41:47
read your motivations,00:41:49
subscribe to the channel so you don't miss the00:41:50
next educational and00:41:52
entertainment videos on the world of00:41:54
programming and now let's see the exercise, we00:41:57
need to create an app that defines00:42:00
three drink price variables equal to 5 euros00:42:03
and 50 cents discount equal to one euro is a00:42:07
favorite customer equal to giacomino00:42:09
or a name of your choice ask00:42:12
the customer what his name is ask the00:42:14
customer how old he is if the customer is00:42:17
called giacomino and is over 25 years old00:42:19
apply a discount to the price of the drink00:42:22
otherwise he won't finally apply print00:42:25
screen the price of the drink with a00:42:27
phrase of your choice if you want to try00:42:29
to solve the exercise on your own00:42:32
pause the video now and dedicate a few00:42:34
minutes to solving there are several00:42:36
ways to solve the exercise00:42:38
be careful because now I'll show you a00:42:40
possible solution let's start by creating00:42:43
the required variables drink price00:42:45
equal to 5 euros and 50 it will be of the flat type00:42:48
discount equal to one euro it will be a00:42:52
favorite customer equal to giacomino it will be a00:42:55
string we print your name on the screen00:42:57
and then with an input function00:43:00
we keep the name entered by the customer00:43:02
in the customer name variable similarly00:43:05
we ask how old you are and save00:43:08
the age entered in customer years after00:43:10
converting it on the fly to the whole number00:43:13
now to decide whether to apply the discount or not you00:43:16
need to write an iv and I00:43:19
will tell you more about the condition of the iv it will be00:43:22
made up of two sub-conditions because00:43:25
we have to verify that the customer's00:43:27
name is giacomino and that he is over 2500:43:30
years old then I write if customer name00:43:34
is equivalent to preferred customer i.e.00:43:36
giacomino and if the customer's age is greater00:43:40
than 25 if this condition is true we take the00:43:43
price of the drink and subtract the discount00:43:45
via the operator an area now first00:43:48
send the cursor still in dictation to00:43:50
add other instructions in the iv but00:43:53
we don't need them so00:43:54
we recommend indenting and insert00:43:56
the final print command the price of the00:43:59
drink is plus the price of the drink converted on the00:44:03
fly in string that's it guys00:44:05
the exercise is unsolved if you00:44:07
solved it differently write it00:44:10
in a comment I'm curious to see and00:44:11
compare your solutions now let00:44:14
's go back to our dearest up at what00:44:16
point we had arrived00:44:18
well we had just told the customer if they00:44:20
are only allowed to order non-00:44:22
alcoholic or even alcoholic drinks, but00:44:25
now I would like to define a list of00:44:27
alcoholic drinks, it is a list of non-alcoholic drinks00:44:29
available in our pack, print00:44:32
these two lists on the screen and allow00:44:34
the customer to choose the00:44:36
desired drinks but how can I create a00:44:39
list of values? very easy let's go back00:44:42
to the explanation file and see it00:44:44
together lists are a very00:44:46
important element of Python and offer a00:44:49
lot of very latest features the00:44:52
list is like a variable except that the00:44:55
variable contains only one value while00:44:57
the list contains many values let's try00:45:00
to create a list of alcohol I write the00:45:03
name of the same alcohol list and open00:45:06
square brackets inside the00:45:09
square bracket I can insert all00:45:11
the elements I want separated by a00:45:13
comma we insert some alcohols of00:45:15
choice in the form of a string mojito00:45:18
comma white russian comma caipirinha that00:45:22
's it if we don't let's get drunk let's00:45:24
close square brackets and our00:45:27
list is ready we have created a00:45:30
homogeneous list of strings but I can00:45:32
also insert integer numbers00:45:34
boolean flops variables of any type00:45:37
in short because a list can00:45:39
also contain heterogeneous data types last let00:45:42
's expand on the screen just like00:45:43
we print the variables print name of the00:45:46
list let's start the program and voilà here's00:45:48
a nice menu with the house drinks to00:45:51
refer to a particular element00:45:53
of the list write the name of the list and00:45:56
open square brackets inside00:45:58
them I write the position of the element00:46:01
that interests me the mojito is in00:46:03
position 0 the white Russian in00:46:05
position 1 is the caipirinha in position00:46:08
2 as you can see in the lists we start00:46:10
counting from zero not from one don't make00:46:13
this mistake then to refer to the00:46:15
mojito I write 0 and close00:46:17
square brackets if I insert this element00:46:20
inside a print it will be printed on the00:46:22
start screen here you go mojito as00:46:25
I was telling you the list offers a lot of00:46:27
very useful functions let's see them00:46:29
together I can count how many elements00:46:32
are present in the list with the00:46:34
len function which stands for length00:46:36
I write allen is in round brackets00:46:39
I insert the name of the list of which to00:46:42
calculate the length then sign the00:46:44
value returned by this function to00:46:46
a variable that I call quantity00:46:48
of alcohol which then is a little screen with00:46:50
a print we start and a00:46:54
nice 3 is printed because in the list on the contents of00:46:56
three elements the list is a set of00:46:59
dynamic elements means that I can00:47:01
add, delete and modify the00:47:04
elements to add a new00:47:05
element to the list use the up function00:47:08
and write the name of the list precisely00:47:10
append and chrome and for every00:47:13
self-respecting function I open the round brackets00:47:16
inside them I insert from the00:47:18
element that I want to add to the00:47:19
list for example ode kiri well so00:47:23
when creating the alcohol list the00:47:27
white Russian mojito and caipirinha drinks are added immediately after00:47:29
the beqiri drink is added via00:47:32
the f function so if there is a little00:47:35
alcohol I start the program here it is00:47:37
I see all four drinks in the list the00:47:40
append function adds the00:47:41
specified element to the end of the list if I00:47:44
want to add an element to the beginning00:47:46
of the list or in any other00:47:49
position I can use the insert function00:47:52
I write the name of the list dot insert00:47:55
is in this function I have to specify00:47:57
two values the first value is an00:48:00
integer which represents the position in00:48:03
which I want to insert the element remember00:48:06
the positions in the lists are counted00:48:08
starting from zero so if I want to00:48:10
insert the new element at the beginning00:48:12
of the list i.e. in the first position00:48:14
I write 0 if I want to insert it for ii or00:48:16
I write one for third I write 2 and so on00:48:20
then we insert a comma and00:48:22
specify the second value which is00:48:24
the element to be inserted in the list for00:48:26
example the martini drink very well if00:48:30
now we have the program here the martini00:48:32
was added in the first position and00:48:34
all the other elements are scaled00:48:36
they can also eliminate an element00:48:39
from the list using the00:48:41
removed function I write the name of the list dot remove and00:48:45
in brackets the name of the element to be00:48:47
eliminated for example white russian00:48:50
let's start the program00:48:52
here now the list contains only mojito and00:48:54
caipirinha alternatively I can00:48:57
delete an element by specifying not00:48:59
its name but its position thanks00:49:02
to the pop function I write alcohol dot00:49:06
pop00:49:07
the white Russian is position 1 so00:49:09
I write 1 we have perfect the result is00:49:13
the same as well as adding and00:49:15
deleting they can also modify an00:49:18
element of the list for example to00:49:20
modify the drink caipirinha I write00:49:23
alcohol it is between squares I write two equal ones00:49:26
and now I specify the new name00:49:29
of the element 2 caipiroska for example00:49:32
we have and now caipirinha has00:49:34
become caipiroska now I show you a00:49:37
very useful function which is used to00:49:39
reorder the elements of a list00:49:42
let's imagine you want to print a nice00:49:44
drinks menu in alphabetical order00:49:47
currently the elements are00:49:48
messy I could sort them manually00:49:51
but I can do it automatically with the00:49:54
sort function I write alcohol dot sort00:49:58
start and voilà drinks are now in00:50:01
alphabetical order we can also concatenate00:50:04
two lists let's imagine we want to create a00:50:07
drink menu that contains both alcoholic00:50:10
and non-alcoholic drinks00:50:11
I have already defined the alcoholic ones so let's00:50:13
also define the non-alcoholic00:50:15
non-alcoholic equals open square lemonade00:50:19
comma a gazzosa closed square now let's00:50:22
create the drink menu list and let's join the00:50:26
two lists thanks to the 'concatenation operator00:50:27
so the drink menus00:50:30
will contain both alcoholic drinks and00:50:32
non-alcoholic drinks we print the is here are00:50:35
all the drinks combined in a delicious00:50:37
menu I can also use the lists in00:50:40
conjunction with the iv declaration the00:50:43
iv declaration offer a00:50:45
very nice functionality for check if a given00:50:48
element is present in a list for00:50:50
example I can write the mojito in00:50:53
alcohol to check if this drink00:50:56
is present in the list if00:50:58
so I can print the drink is00:51:00
available if I start the program here is00:51:03
the message if I go back to the00:51:05
written code the name of a drink that00:51:07
doesn't exist here is nothing message well00:51:10
now that we have learned the many beautiful00:51:12
functions offered by the lists00:51:13
let's try to use them for what00:51:16
interests us we wanted to list to the customer the00:51:18
drinks offered in our memories so let00:51:21
's write here are the alcoholic drinks00:51:23
available and then let's print all the00:51:26
elements of the alcoholic list one after00:51:28
the other how to do it well we have learned00:51:31
that it is sufficient to write print00:51:33
alcoholic but if I try to start00:51:36
the list it is printed with squares,00:51:38
quotes and commas it is not very nice00:51:41
to look at and it would be better print the00:51:43
drinks one at a time line by line well00:51:45
but we have learned that we can00:51:47
print only one element of the list00:51:49
by writing alcohol is between squares the00:51:53
number of the element we start from zero00:51:55
now we add some primes with the00:51:57
other two elements both plus the program00:51:59
works now it comes printed a00:52:02
nice tidy and understandable list but00:52:04
let's go back to the code to print00:52:07
this list we repeated the same00:52:09
print three times every time you00:52:12
happen to write code in a00:52:14
repetitive way a question must immediately come to00:52:16
mind is there a simpler way00:52:18
more short is repetitive to00:52:21
do what I'm doing after all00:52:23
programming itself was created precisely to00:52:25
solve long and repetitive pockets and00:52:28
in fact there is a00:52:30
very important programming principle00:52:32
called j j stabler tod's group it00:52:35
yourself or don't repeat another00:52:38
principle that I like a lot is the kiss00:52:40
means keep it simple stupid or00:52:44
keep the code simple stupid00:52:46
this principle serves to remind us in a00:52:48
rather irreverent tone that we must00:52:51
avoid unnecessary complications00:52:53
when we write code the00:52:55
programming principles there are many others and00:52:58
they are very useful to keep in mind00:53:00
so I invite you to explore them. I want to00:53:02
end with a splendid quote from00:53:04
John Wood, a historian of00:53:07
video game programmers. He says, write some code,00:53:10
imagining that the colleague who will have00:53:12
to work on it in the future is a violent00:53:14
psychopath who knows where you live.00:53:17
This last sentence certainly motivates us00:53:19
to write simple code. non-00:53:21
repetitive now here we have repeated a00:53:23
simple print only three times it's not00:53:26
too much but imagine if the list was00:53:28
made up of not 3 mattia c drink we would have00:53:32
had to write 10 prints and imagine if00:53:35
we deleted or added new00:53:37
ones the list we would have to return to the00:53:39
point where it came from printed and make00:53:41
complex and inconvenient modifications so00:53:44
I want to print the list in a00:53:46
simpler and more efficient way to avoid00:53:48
problems and visits from00:53:50
psychopaths, after all we are interested in00:53:53
printing all the elements of the list00:53:56
whether they are many or few but how can we00:53:58
efficiently extract one by one00:54:01
all the elements of a list to00:54:03
print them with a printer or use it in00:54:05
other ways there is a00:54:07
fundamental element of programming that is00:54:09
right for our case00:54:11
it is used to repeat one or more lines of00:54:13
code automatically and goes very00:54:15
well with lists Ladies and gentlemen,00:54:18
let's delete this cycle four00:54:21
which shouldn't be seen and let's get to know the00:54:24
form cycle together. First I'll write it down and then I'll explain it to you.00:54:37
Italian00:54:39
we read for each alcohol in the00:54:44
alcohol list print alcohol in practice00:54:47
we are telling the program to extract00:54:49
each alcohol from the alcohol list and00:54:52
print it each time with a print and in00:54:54
fact this print will be00:54:57
automatically repeated many times in this00:55:00
case three times because the elements of the00:55:03
list are three if we add other00:55:05
instructions preceded by temptation00:55:07
they will also be repeated after the00:55:10
print technically the four cycle00:55:12
works like this the alcohol list is taken as reference is00:55:14
elected the first00:55:17
element of the list is saved in the00:55:20
alcohol variable so at this point00:55:22
the alcohol variable will be equal to many00:55:25
we can use this variable00:55:27
as we wish for example in an open00:55:29
once the fried and any00:55:32
other given instructions have been00:55:34
executed the cycle starts again00:55:37
now it is elected the second element00:55:39
of the list is saved in the00:55:41
alcoholic variable the variable has therefore changed00:55:43
value now it is equal to white russian the00:55:47
dictated instructions are executed and the00:55:49
cycle starts again the third00:55:52
value is saved on alcoholic which will00:55:54
now be equal to caipirinha00:55:57
the invented instructions are executed once again00:55:59
now in the alcohol list there are no00:56:01
more elements to read therefore the loop00:56:03
ends I can't wait to start the00:56:05
program to see the loop four in00:56:07
actions via wow fantastic with a few00:56:11
lines of code I saw the list00:56:13
of alcohol printed interesting no00:56:15
instead of manually writing a print00:56:17
for each item in the list we use the00:56:20
loop holes to automatically execute00:56:22
a print for all the elements of the00:56:25
list it doesn't matter if there are three or if there are00:56:27
100 of them it will consider all of them the00:56:30
alcoholic variable is called the00:56:33
loop variable I called it alcoholic but00:56:36
I could call it drink element or even00:56:39
just peak but call it alcohol in00:56:42
alcohols makes everything much more00:56:45
readable no in fact as a00:56:47
loop variable we always try to use the name00:56:49
of the list in the singular as we00:56:51
said the loop four repeats the00:56:54
invented instructions as many times as there are00:56:57
elements in the list but we can also00:56:59
interrupt the loop if a00:57:02
condition decided by us occurs, for example00:57:04
I want the cycle to print mojito and00:57:07
white russian but end before00:57:10
printing caipirinha I can use an00:57:12
iv declaration inside the00:57:15
four cycle before the first I insert00:57:18
alcoholic iv equivalent to white russian brake00:57:21
this command is needed to interrupt the00:57:25
cycle these changes mean that00:57:27
on the second repetition of the cycle00:57:29
when alcoholic will be equal to white00:57:31
russian00:57:32
the brake command will be executed so the00:57:35
cycle will interrupt before executing00:57:38
the underlying print which would have00:57:40
printed white russian and will not00:57:42
even execute the following repetition related00:57:45
to caipirinha if we execute the code here is00:57:48
the print and it is executed only for00:57:50
mojito we also have a command similar00:57:53
to the break which is called continue this00:57:55
command does not end the entire cycle but00:57:58
only ends the current repetition00:58:00
therefore on the second repetition when00:58:03
alcoholic it will be equal to white russian the00:58:05
continuous command will be executed and the00:58:08
repetition will be terminated without00:58:10
executing the prince after which the cycle00:58:12
will continue normally with the last00:58:15
repetition in fact if we start the00:58:17
program we see that the only element00:58:19
not printed is white russian00:58:22
very well we have seen that the cycle00:58:24
four is a very dear friend of lists00:58:26
because it offers a lot of00:58:28
useful features to manage them but it is not00:58:30
only used with lists we can use the00:58:32
four loop with all the iter-00:58:35
able elements another iter-able element are00:58:37
the strings if I write for each00:58:40
letter in the edo bot string and print00:58:43
the letter cycle variable by starting00:58:46
the program a print will be executed00:58:48
for each edo bot letter00:58:51
finally the four cycle can be00:58:53
used with a range of numbers if you00:58:55
need all the numbers from 1 to 18 for00:58:58
example I write for each number of the00:59:02
range function00:59:04
1.19 the rage function returns a series00:59:08
of numbers that go from the first to the second00:59:10
specified value the first value is00:59:13
included in the series the second is excluded00:59:16
and for this reason if I am interested in the00:59:18
numbers from 1 18 I write 1 19 we print the00:59:22
cycle variable we start is done00:59:26
very well after having familiarized ourselves00:59:28
well with the lists here is the cycle four00:59:30
we are ready to apply the knowledge00:59:32
learned to our virtual barista app00:59:35
we immediately insert the two new00:59:37
alcoholic and non-alcoholic lists very well00:59:40
now immediately after presenting the00:59:43
special drink digital vodka let's say nothing00:59:46
how many alcoholic and non-alcoholic drinks are00:59:49
available I write print is after a new00:59:52
line character to distance a little00:59:54
from the previous message I write the00:59:57
alcoholic drinks are more and remember with the01:00:01
len function we get the length01:00:04
of the interested list here's attention to01:00:07
the length it will be an integer01:00:09
so to be able to concatenate it and01:00:12
we convert it into a string like this very well01:00:14
I do the same for non-alcoholic drinks01:00:17
now if I start the yes program01:00:20
here are the two new messages that tell me01:00:22
how many alcoholic and non-alcoholic drinks are01:00:25
present in the respective lists01:00:27
well now we have to ensure that for01:00:29
underage customers only non-01:00:31
alcoholic drinks are available while for adults01:00:34
both alcoholic and non-alcoholic drinks are available,01:00:36
then after calculating the customer's age01:00:39
we create a list called01:00:42
available drinks which for now will be empty if the01:00:45
customer is a minor after printing01:00:46
this message01:00:48
we add it to the same iv plus01:00:51
non-alcoholic drinks, i.e. we are01:00:54
adding the non-alcoholic drinks to the01:00:56
available drinks, if instead the01:00:58
adult customer is assigned01:01:01
the result of the01:01:03
concatenation of the non-alcoholic and01:01:06
alcoholic lists to available trinkets so all the drinks will be01:01:08
present in the available drinks list,01:01:11
now as we have learned we print01:01:13
all the available drinks using a01:01:15
nice for cycle, first we print the01:01:18
recommended drinks for you and then for each01:01:21
drink available in the list of01:01:24
available drinks, we print available drinks now,01:01:27
finally we give the customer the opportunity01:01:29
to choose a drink and we save01:01:32
his choice in the chosen drink variable,01:01:34
finally if the drink chosen by01:01:37
the customer is present among the01:01:39
available drinks we print you have chosen more01:01:42
drink chosen more good aperitif01:01:45
otherwise we print I'm sorry the01:01:48
drink chosen drink is not available with01:01:51
a sad face our01:01:53
virtual bartender is very emotional I must say01:01:55
fantastic now our virtual bartender app01:01:58
it's almost finished let's try to01:02:01
test it by making different choices let's start01:02:04
enter your year of birth01:02:06
2005 you're a minor here are the01:02:09
recommended drinks for you lemonade and soda01:02:12
perfect I'll choose soda you've chosen01:02:16
soda have a good aperitif now let's try again01:02:18
with an age greater than 1801:02:21
start01:02:22
1995 here it is the drinks now01:02:25
also include alcohol I choose mojito good01:02:29
aperitif fantastic now let's restart01:02:32
let's say a year and let's try to insert01:02:35
a drink not on the list street I'm01:02:40
sorry the spritz drink is not01:02:42
available excellent it works very well but after01:02:46
this message the program ends01:02:48
without the customer has chosen an01:02:50
available drink, it would be nice if after01:02:53
this message the01:02:56
list of available drinks was presented again and so the01:02:58
customer could try to choose again. To be01:03:00
precise, let's go back to the code. I01:03:03
want this entire01:03:06
portion of the code to be repeated in which01:03:08
the recommended drinks are printed.01:03:10
customer choice and confirmation messages are printed01:03:13
this portion of code01:03:15
must be repeated until the customer01:03:18
chooses an available drink but how01:03:22
can we repeat a portion of code01:03:25
until a given condition is satisfied01:03:27
it is really easy01:03:30
let's move to our good01:03:32
explanations file let's see it together01:03:34
to repeat one or more instructions as long as01:03:37
a given condition remains respected we01:03:40
use the while loop which in English01:03:43
means as long as we take an example the01:03:46
variable a is equal to 1 now we write01:03:50
a while loop as long as the variable a is01:03:54
less than 5 for example a colon at the beginning with01:03:59
indentation we write a print tiger01:04:03
against tiger let's immediately see what happens01:04:05
by trying to start the tiger program01:04:08
with all the cats that with three tigers01:04:09
more against the many experienced the seizure01:04:12
the program is printing this01:04:14
message infinitely how come we01:04:16
block it forcibly and let's go back to the01:04:19
code a wilde loop is made up of three01:04:21
elements the keyword while or01:04:25
until a condition to be respected01:04:27
just like in the iv declarations and01:04:29
finally one or more lines of code01:04:31
preceded by temptation which will01:04:34
continue to be printed as long as01:04:36
this condition remains true01:04:38
when this condition becomes false01:04:41
the cycle ends01:04:43
and for this reason tiger against tiger01:04:45
is printed infinitely because the01:04:47
variable a is equal to 11 and less than01:04:50
five therefore this condition is true and01:04:53
since the variable a is never01:04:55
modified the condition will be true01:04:58
forever so the print will be executed01:05:01
infinitely let's try to print and01:05:03
inside the print the value of the01:05:05
variable a let's start here a is always01:05:08
equal to 1 as expected01:05:10
now let's do something a little more01:05:12
interesting with each repetition01:05:14
after having printed a let's increase of kudo01:05:17
its value that's it let's start and01:05:20
look a bit the numbers01:05:23
from 1 to 4 are printed and then the cycle is interrupted01:05:27
how come let's go back to the code and I'll explain01:05:29
at the beginning of the while loop it is01:05:31
checked if a and less than 5 this01:05:35
condition is true because a is equal to 101:05:38
then the first01:05:39
repetition of the cycle is executed or a is01:05:42
printed and then it is increased by01:05:45
one so now a is equal to 2 the01:05:48
repetition is finished so it01:05:50
starts again from the beginning01:05:52
the condition a is checked again and is still01:05:55
less than five because it is equal to 201:05:57
so it is printed on the screen again and01:05:59
is increased the cycle will continue like this01:06:02
until stripping 4 the variable will be01:06:06
printed on the screen increased by one01:06:08
depriving it at 5 now the condition will no01:06:11
longer be true so the loop will end which is01:06:14
why on the screen we see the01:06:16
numbers from 1 to 4 printed also the while loop01:06:19
like the four loop has the01:06:21
continuous command to forcibly interrupt01:06:23
a repetition and the brake command to01:06:26
interrupt the entire cycle let's make01:06:28
another example of a while loop01:06:30
using it to create a little game01:06:32
this little game will consist in a01:06:34
riddle to which the customer will have to01:06:36
answer if the customer's answer01:06:38
is wrong the riddle will continue to01:06:41
be repeated endlessly until the01:06:44
customer guesses the01:06:46
correct answer we create an infinite loop01:06:48
by writing while he as the01:06:51
through condition by explicitly writing through01:06:53
therefore true as condition it will01:06:56
always be true it will make the loop infinite01:06:59
but don't be scared we will end it01:07:02
manually with the brake command now01:07:05
we write the riddle that a01:07:08
bird asks inside a computer and01:07:11
we acquire the customer's answer with01:07:13
the input function saving it in the01:07:15
answer variable now if answer is01:07:18
equivalent on chip we escape the01:07:22
correct answer and end the cycle thanks to the01:07:25
bray command otherwise we write01:07:27
try again and go to the beginning without a break01:07:30
so the cycle will repeat itself proposing01:07:33
the excellent riddle again let's try to start01:07:36
the little game that a bird plays inside01:07:38
a computer barks try again replaces01:07:41
the RAM not even go chip correct answer is01:07:46
the cycle ends for fandom now guys let's01:07:49
finally complete our01:07:50
beautiful virtual barista up01:07:53
by implementing the while loop just01:07:55
learned remember we wanted to repeat01:07:58
this entire portion of code if the customer01:08:01
orders a drink that is not among the01:08:03
available drinks then we insert a01:08:06
infinite loop or with always01:08:09
through condition and we indent the whole portion01:08:12
to be reflected we can do it quickly01:08:14
by selecting and using the short cut shift01:08:18
ab on the keyboard that's it now since01:08:21
the loop is basically the finite01:08:23
we have to decide how to end it very01:08:26
simple when the customer chooses a01:08:28
drink available and will be ready for01:08:30
the aperitif let's add the brake command01:08:33
to end the cycle very well guys01:08:35
now the app for our fantastic pub01:08:38
drinks and codes is finally finished it01:08:42
was a long but very01:08:44
rewarding job because we overcame a01:08:46
lot of problems01:08:47
learning a lot01:08:49
after all, this is what01:08:52
always happens when you start01:08:54
creating an app,01:08:55
now that it's finished, let's try it01:08:57
together immediately, first of all, I thank you very01:09:00
much for following this tutorial, I01:09:02
created it trying to convey to you01:09:04
all my great passion for the01:09:06
world of programming which is a01:09:08
truly fun creative world is01:09:10
full of professional opportunities01:09:12
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[ Music]Description:
📖 In solo 1 ora impara a programmare in modo Pratico e Divertente! Creiamo insieme un Assistente Virtuale, imparando tutti i concetti di programmazione fondamentali. Il Python è il miglior linguaggio per imparare a programmare perché è Semplice ma molto Potente. Al termine di questo corso sarai in gradi di programmare in Python le app che desideri. Impara subito come programmare, è facile! 🙂 👩🏻💻 Diventa Web Developer con Epicode! https://epicode.com/it/landing-web-developer-a/ 📌 PARTITA IVA con Fiscozen: consulenza GRATIS e 50€ di sconto ⏩ https://www.fiscozen.it/promo/partner/ 🔖 Acquista il mio corso Python per Principianti a Prezzo Scontato! https://www.pitoneprogrammatore.com/ TUTTI I CAPITOLI A PORTATA DI CLICK: 00:02:18 Scaricare e Installare Python 00:04:33 Stampare messaggi a schermo 00:08:06 Le Variabili 00:14:34 Scrivere degli input al programma 00:18:31 Calcoli Matematici 00:20:27 Operatori Unari 00:22:52 Concatenare le Stringhe 00:25:17 Errori ed Eccezioni 00:25:53 Conversioni di Tipi di Dati 00:28:21 I Commenti 00:32:31 Dichiarazione IF 00:39:02 Operatori Booleani 00:41:57 Un piccolo Esercizio 00:44:37 Le Liste 00:54:17 Il Ciclo FOR 01:03:41 Il Ciclo WHILE #--- Programmare in python tutorial ita è semplice. In questo corso python per principianti impareremo la programmazione in modo facile e divertente. Un tutorial python completo per capire come programmare in python e imparare a programmare in questo corso di programmazione. Questo tutorial programmazione python ti darà le basi della programmazione python per principianti. Progammazione ita, questo corso ti insegna rapidamente come programmare da zero i linguaggi di programmazione. ---#
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