5.7 KiB
5.7 KiB
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Python Boolean Operations |
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:
- This is a short-circuit operator, so it only evaluates the second argument if the first one is False.
- This is a short-circuit operator, so it only evaluates the second argument if the first one is True.
not
has a lower priority than non-Boolean operators, sonot a == b
is interpreted asnot (a == b)
, anda == 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:
- This is a short-circuit operator, so it only evaluates the second argument if the first one is True.
- 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