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Engineering LibreTexts

3.1: Boolean Expressions

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 class bool; they are not strings:

 

>>> type(True)
<class 'bool'>
>>> type(False)
<class 'bool'>

The == operator is one of the comparison 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
      x is y               # x is the same as y
      x is not y           # x is not the same as y

Although these operations are probably familiar to you, the Python symbols are different from the mathematical symbols for the same operations. 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 comparison operator. There is no such thing as =< or =>.