CS105: Introduction to Python

Equality and relational operators

Equality operators

An equality operator checks whether two operands' values are the same (==) or different (!=). 

Note that equality is ==, not just =.

Equality operators	Description	Example (assume x is 3)
==	a == b means a is equal to b	x == 3 is true x == 4 is false
!=	a != b means a is not equal to b	x != 3 is false x != 4 is true

An expression evaluates to a Boolean value.
A Boolean is a type that has just two values: True or False

Relational operators

A relational operator checks how one operand's value relates to another, like being greater than.

Relational operators	Description	Example (assume x is 3)
<	a < b means a is less than b	x < 4 is true x < 3 is false
>	a > b means a is greater than b	x > 2 is true x >3 is false
<=	a <= b means a is less than or equal to b	x <= 4 is true x <= 3 is true x <= 2 is false
>=	a >= b means a is greater than or equal to b	x >= 2 is true x >= 3 is true x >= 4 is false

Operator chaining

Python supports operator chaining.
Example:
a < b < c
determines whether b is greater-than a but less-than c.
Chaining performs comparisons left to right,
evaluating a < b first.

• If the result is true, then b < c is evaluated next.
• If the result of the first comparison a < b is false, then there is
• no need to continue evaluating the rest of the expression.