bool() in Python

The bool() method is used to return or convert a value to a Boolean value i.e., True or False, using the standard truth testing procedure.
Syntax:

bool([x])

The bool() method in general takes only one parameter(here x), on which the standard truth testing procedure can be applied. If no parameter is passed, then by default it returns False. So, passing a parameter is optional. It can return one of the two values.

  • It returns True if the parameter or value passed is True.
  • It returns False if the parameter or value passed is False.

Here are few cases, in which Python’s bool() method returns false. Except these all other values return True.



  • If a False value is passed.
  • If None is passed.
  • If an empty sequence is passed, such as (), [], ”, etc
  • If Zero is passed in any numeric type, such as 0, 0.0 etc
  • If an empty mapping is passed, such as {}.
  • If Objects of Classes having __bool__() or __len()__ method, returning 0 or False
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# Python program to illustrate
# built-in method bool()
  
# Returns False as x is False
x = False
print(bool(x))
  
# Returns True as x is True
x = True
print(bool(x))
  
# Returns False as x is not equal to y
x = 5
y = 10
print(bool(x==y))
  
# Returns False as x is None
x = None
print(bool(x))
  
# Returns False as x is an empty sequence
x = ()
print(bool(x))
  
# Returns False as x is an emty mapping
x = {}
print(bool(x))
  
# Returns False as x is 0
x = 0.0
print(bool(x))
  
# Returns True as x is a non empty string
x = 'GeeksforGeeks'
print(bool(x))

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Output:

False
True
False
False
False
False
False
True

Application

Here is a program to find out even and odd by the use of bool() method. You may use other inputs and check out the results.
Example:

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# Python code to check whether a number 
# is even or odd using bool()
  
def check(num):
    return(bool(num%2==0))
  
# Driver Code
num = 8;
if(check(num)):
    print("Even")
else:
    print("Odd")

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Output:

Even


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