Truth Value Testing in Python

September 12, 2023

Truth Value Testing

We can use any way to check the truth value of an object . By using ‘If’ statement or ‘While’ statement the checking can be done. By default, an object is considered true unless its class defines either a __bool__() method that returns False or a __len__ method that returns zero, when called with the object.

Truth Value Testing :

The truth value 0 is equivalent to False and 1 is same as True.
When a variable contains different values like 0, 0.0, Fraction(0, 1), Decimal(0), then it signifies the False Value.
Truth value of an empty sequence is False.

Example :

x=1
- bool(x)=True
x=1
- if(x==1):
  - print(‘True’)

Code :

Run

#python Program 
#The class Prep has no __bool__ method, so default value of it is True
class Prep: 
   def __init__(self):
      print('This is class Prep')
        
p_obj = Prep()
if p_obj:
   print('It is True')
else:
   print('It is False')
#The class Insta has __bool__ method, which is returning false value    
class Insta: 
   def __init__(self):
      print('This is class Insta')
        
   def __bool__(self):
      return False
I_obj = Insta()
if I_obj:
   print('It is True')
else:
   print('It is False')
Tupl = (4,7, 8,41) # Some elements are available, so it returns True
if Tupl:
   print('Not Empty')
else:
   print('Empty')
lis = [] # No element is available, so it returns False
if lis:
   print('Not Empty')
else:
   print('Empty')

Output:

This is class Prep
It is True
This is class Insta
It is False
Not Empty
Empty

Using Step In a Slicing

String Operators in Python

String Replacement Fields in Python

F-Strings in Python

String Interpolation in Python

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