18.2: Boolean Expressions
- Page ID
- 15377
A boolean expression is an expression that is either true or false. The following examples use the operator ==
, which compares two operands and produces True
if they are equal and False
otherwise:
>>> 5 == 5 True >>> 5 == 6 False
True
and False
are special values that belong to the type bool
; they are not strings:
>>> type(True) <type 'bool'> >>> type(False) <type 'bool'>
The ==
operator is one of the relational operators; the others are:
x != y # x is not equal to y x > y # x is greater than y x < y # x is less than y x >= y # x is greater than or equal to y x <= y # x is less than or equal to y
Although these operations are probably familiar to you, the Python symbols are different from the mathematical symbols. A common error is to use a single equal sign (=
) instead of a double equal sign (==
). Remember that =
is an assignment operator and ==
is a relational operator. There is no such thing as =<
or =>
.