Python Boolean Operations


title: Python Boolean Operations

or, and, not

Python Docs – Boolean Operations

These are the Boolean operations, ordered by ascending priority:

Operation | Result | Notes --------- | ------------------------------------ | ----- x or y | if x is false, then y, else x | (1) x and y | if x is false, then x, else y | (2) not x | if x is false, then True, else False | (3)

Notes:

  1. This is a short-circuit operator, so it only evaluates the second argument if the first one is False.
  2. This is a short-circuit operator, so it only evaluates the second argument if the first one is True.
  3. not has a lower priority than non-Boolean operators, so not a == b is interpreted as not (a == b), and a == not b is a syntax error.

Examples:

or:

>>> True or False # Short-circuited at first argument. True >>> False or True # Second argument is evaluated. True >>> False or False # Second argument is evaluated. False

and:

>>> True and False # Second argument is evaluated. False >>> False and True # Short-circuted at first argument. False >>> True and True # Second argument is evaluated. True

not:

>>> not True False >>> not False True

How python sees True and False

For python True==1 and False==0

1 and False //False 0 and 1 //False 1 and True //True 1 or 0 //True

Other boolean-operations:

These are other boolean operations which are not part of the Python language, you will have to define them yourself or use the boolean expression within the parenteses.

Operation | Result | Notes --------- | ------------------------------------ | ----- nand ( not (x and y) ) | if x is True, then y, else x | (1) nor ( not (x or y) ) | if x is False, then x, else y | (2) xor ( not (not (x or y) or (x and y)) ) | | xnor ( not (x or y) or (x and y) ) | |

Notes:

  1. This is a short-circuit operator, so it only evaluates the second argument if the first one is True.
  2. This is a short-circuit operator, so it only evaluates the second argument if the first one is False.

Examples:

nand:

Used in a defined way:

def nand(x, y): return not(x and y)

output:

>>> nand(True, True) # Short-circuited at first argument. False >>> nand(False, True) # Second argument is evaluated. True >>> nand(True, False) # Short-circuited at first argument. True >>> nand(False, False) # Second argument is evaluated. True

Used in a direct way:

if not(x and y): do something....

output:

>>> not(True and True): # Short-circuited at first argument. False >>> not(True and True) # Second argument is evaluated. True >>> not(True and True) # Short-circuited at first argument. True >>> not(True and True) # Second argument is evaluated. True

nor:

Used in a defined way:

def nor(x, y): return not(x or y)

output:

>>> nor(True, True) # Short-circuited at first argument. False >>> nor(False, True) # Second argument is evaluated. False >>> nor(True, False) # Short-circuited at first argument. False >>> nor(False, False) # Second argument is evaluated. True

Used in a direct way:

if nor(x or y): do something....

output:

>>> not(True or True): # Short-circuited at first argument. False >>> not(True or True) # Second argument is evaluated. False >>> not(True or True) # Short-circuited at first argument. False >>> not(True or True) # Second argument is evaluated. True

xor:

Used in a defined way:

def xor(x, y): return not(not(x or y) or (x and y))

output:

>>> xor(True, True) False >>> xor(False, True) True >>> xor(True, False) True >>> xor(False, False) False

Used in a direct way:

if not(not(x or y) or (x and y)): do something....

output:

>>> not(not(True or True) or (True and True)): # Short-circuited at first argument. False >>> not(not(True or False) or (True and False)) # Second argument is evaluated. True >>> not(not(False or True) or (False and True)) # Short-circuited at first argument. True >>> not(not(False or False) or (False and False)) # Second argument is evaluated. False

xnor:

Used in a defined way:

def xnor(x, y): return not(x or y) or (x and y)

output:

>>> xnor(True, True) True >>> xnor(False, True) False >>> xnor(True, False) False >>> xnor(False, False) True

Used in a direct way:

if not(x or y) or (x and y): do something....

output:

>>> not(not(True or True) or (True and True)): # Short-circuited at first argument. True >>> not(not(True or False) or (True and False)) # Second argument is evaluated. False >>> not(not(False or True) or (False and True)) # Short-circuited at first argument. False >>> not(not(False or False) or (False and False)) # Second argument is evaluated. True

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