Built-in bool() function
You can check if a value is either truthy or falsy with the built-in bool() function. This function 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(parameter)
You only need to pass the value as an argument.
Example:
Python3
bool(7) # True bool(0) #False bool([]) # False bool({7,4}) #True bool(-4) # True bool(0.0) # False bool(None) # False bool(1) #True bool(range(0)) # False bool(set()) # False bool([1,2,3,4]) # True |
Output:
True False False True True False False True False False True
Now let’s see a program for better understanding of Truthy and Falsy value.
Example:
Python3
# define a function for checking # number is even or odd def even_odd(number): if number % 2: # since num % 2 is equal to 1 # which is Truthy Value return 'odd number' else: # since num%2 is equal to 0 # which is Falsy Value. return 'even number' result1 = even_odd(7) # prints odd print(result1) result2 = even_odd(4) # prints even print(result2) |
Output:
odd number even number
Since in first function call num % 2 is equal to 1 which is Truthy Value, so output is ‘odd number’ and in second function call num % 2 is equal to 0 which Falsy Value, so output is ‘even number’.
Truthy vs Falsy Values in Python
In this article, we will see about the concept of Truthy and Falsy values in Python and also see how to determine a value is Truthy or Falsy by using bool() built-in Python function.
Now, Let’s start with the following two codes:
Python3
number = 7if number: print(number) |
Output:
7
Let’s change value of number to 0
Python3
number = 0if number: print(number) |
Output:
There is no Output
Have you wondered why the above code run successfully despite number not being an expression?
The answer lies in concept of Truthy and Falsy Values.
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