Python If Statement

Python supports the usual logical conditions from mathematics:

a == b

a != b

a <= b

a >= b These conditions can be used in several ways, most commonly in "if statements" and loops. An "if statement" is written by using the if keyword.

In this example we use two variables, a and b, which are used as part of the if statement to test whether b is greater than a.

is 33, and b is

The if statement evaluates a condition (an expression that results in

). If the condition is true, the code block inside the if statement is executed. If the condition is false, the code block is skipped.

Checking if a number is positive:

Python relies on indentation (whitespace at the beginning of a line) to define scope in the code. Other programming languages often use curly-brackets for this purpose.

If statement, without indentation (will raise an error):

# you will get an error

You can use spaces or tabs for indentation, but you must use the same amount of indentation for all statements within the same code block.

You can have multiple statements inside an if block. All statements must be indented at the same level.

Multiple statements in an if block:

Boolean variables can be used directly in if statements without comparison operators.

Python can evaluate many types of values as

False in an if statement. Zero (

), empty strings ( "" ), None, and empty collections are treated as

True. This includes positive numbers (

), negative numbers ( -3

"False" is treated as