If else statements

In Python you can define conditional statements, known as if-statements.
A block of code is executed if certain conditions are met.

If statements

Consider this application, it executes either the first or second code depending on the value of x.

#!/usr/bin/python   x = 3 if x < 10: print("x smaller than 10") else: print("x is bigger than 10 or equal")

If you set x to be larger than 10, it will execute the second code block.   We use indentation (4 spaces) to define the blocks.

A little game:
A variable may not always be defined by the user, consider this little game:

age = 24   print "Guess my age, you have 1 chances!" guess = int(raw_input("Guess: "))   if guess != age: print("Wrong!") else: print("Correct")

Conditional operators

A word on conditional operators

Operator	Description
!=	not equal
==	equals
>	greater than
<	smaller than

Do not confuse the assignment operator (=) with the equals operator (==).

Nesting

The most straightforward way to do multiple conditions is nesting:

a = 12 b = 33   if a > 10: if b > 20: print("Good")

This can quickly become difficult to read, consider combining 4 or 6 conditions.  Luckily Python has a solution for this, we can combine conditions using the andkeyword.

guess = 24 if guess > 10 and guess < 20: print("In range") else: print("Out of range")

Sometimes you may want to use the or operator.