while True:
    print('You are nice!')
    answer = input('Should I stop saying that? Write yes in that case.')
    if answer == 'yes':
        break
            

i = 0
while i < 100: 
    if i % 2 == 0: # continue with the next repetition if i is divisible by 2
        continue
    print(i,'is an odd number')
            

temp = int(input('What is the temperature?'))
if temp > 20:
    print('Warm and nice!')
elif temp > 0: #if temp <= 20 and temp > 0
    print('Not very cold, but not so warm either.')
            

number = int(input('Enter an integer'))
if number == 0:
    print('You entered the number 0.')
elif number > 0:
    print('You entered a positive number.')
else:
    print('You entered a negative number.')
            

age = int(input('How old are you?'))
if age >= 18:
    print('You are an adult!')
else:
    print('You are not an adult.')
            

float('0.01')  #converts the string '0.01' to 0.01
float(10)  #converts the integer 10 to 10.0
            

number = 10
if number == 10:
    print('The number is equal to 10.') #this will be printed
            

number = int(input('Enter an integer'))
if number == 0:
    print('You entered the number 0.')
elif number > 0:
    print('You entered a positive number.')
else:
    print('You entered a negative number.')
            

answer = input('What is your name?')  #The user's answer is saved in the variable answer
            

int(42)  #converts the string '42' to 42
int(3.94)  #converts the decimal number 3.94 to 3
            

print('Hello World')  #prints "Hello World"
print(1+1) #prints the number 2
print(x)  #prints the content of variable x
            

print('Hello World', end='')  #prints "Hello World" without a new line
            

print('Hello','to','you')  #Prints "Hello to you"
print('Hello','to','you',sep=' | ',end='!')  #prints "Hello | to | you!" without a new line at the end.
            

from random import randint
roll = randint(1,6)  #a random number 1-6
            

round(7.89)  #rounds to 8
round(1.23)  #rounds to 1
            

round(1.23456,2)  #rounds 1.23
round(1.23456,4)  #rounds to 1.2346
            

str(2.71)  #converts the decimal number 2.71 to the string '2.71'
str(10)  #converts the integer 10 to '10'
            

age = 15
print('You are ' + str(age) + ' years old.')
            

n = int(input('How many numbers do you want to print?'))
i = 1
while i <= n:
    print(i)
    i = i + 1
            

Introduction

Here you will learn about

• What Python is and what kind of language it is
• What indentation is and why it is important in Python
• What a comment in the code looks like

What is Python?

Python is a programming language that is relatively easy to write and read. It was created in 1991 by Guido van Rossum. Python 3 was launched in 2008 and it is the version of Python used here at Pythonlab.dev.

Python is an interpreted language, which means that the code is interpreted while the program is running. There are a number of advantages to this, including that the code can easily be run on different platforms (Windows, Mac, Linux). A major disadvantage is that interpreted languages are slower than languages that convert the code to machine code (ones and zeros), which are called compiled languages.

Nowadays, Python is one of the world's most popular programming languages. Major areas of use are web apps, AI (artificial intelligence or machine learning) and scientific calculations. But Python can be used for most things.

Indentation

Indentation means that one or more lines are to the right of the text above. Look through the example below.

Here first two lines of text
that have no indentation.
    Here comes indented text and
    these green-marked lines belong to
    the same block.
Now we are back to text without indentation.
Here is another line.
    Here is a block that is indented and
    these blue lines are one and the same block.
        Now we are at the next level of indentation.
This line has no indentation.

All lines indented above are colored. The lines that have the same color have the same indentation and belong to the same block. What a block means you will learn later in this course.

A line is indented with four spaces. Here at Pythonlab.dev you can also use the TAB key, which is located above Caps Lock, and then four spaces are automatically written. This is also how many other editors used for writing code work.

In many programming languages braces { } are used to show which lines belong together. In Python, this is done with indentation. In other languages indentation is just a recommendation and the program works just as well without it. In Python, indentation is an important part of the language and the program cannot be run if the indentation is incorrect.

-- Output from your program will be here --

In the code above, you can see that some words are blue and the number 3 is green. It is common in programming to use an editor that highlights keywords, built-in functions, numbers, etc. with different colors. Color coding is used to make the code easier to read and to find errors faster.

Comments

When programming, it is often important to write code that others can understand. It is also important for your own sake. It is surprisingly difficult to remember how code you have written yourself works, even a short time afterwards.

A comment is plain text that is ignored by the computer. Using comments makes the code easier and faster to understand. For example, by briefly describing the purpose of a block of code with a comment.

In Python, comments are written with the symbol #; subsequent text is considered a comment and is not part of the program code.

# This is a comment
import math #here we import Python's math library.
print(math.pi) #prints pi

-- Output from your program will be here --