In Python you can define conditional statements, known as if-statements.
A block of code is executed if certain conditions are met.
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")
A word on conditional operators
Do not confuse the assignment operator (=) with the equals operator (==).
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 and keyword.
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.