Use logical operators

The logical operators in Python (and, or, not) are often used in the if, if…else, and if…elif statements. They enable you to make multiple comparisons inside a single statement, such as to determine whether a value is within a certain range. Consider the following example:

x = int(input('Enter your age: '))

if x < 21 or x > 100:
    print('You are too young or too old, go away!') 
else:
    print('Welcome, you are of the right age!')

Here is the output of the various inputs:

Enter your age: 14
You are too young or too old, go away!
>>> 
Enter your age: 101
You are too young or too old, go away!
>>> 
Enter your age: 25
Welcome, you are of the right age!
>>>

The code above checks to see if the user has entered a value less than 21 or greater than 101 (if x < 21 or x > 100) and if that is the case, the user is informed that she is too young or too old. If the user enters any other number between 21 and 100, the Welcome, you are of the right age! message will be displayed.

Here is another example:

x = int(input('Enter your age: '))

if x > 0 and x < 21:
    print('Oww, you are still a child!') 
elif x > 21 and x < 40:
    print('You are so young!')
elif x > 40 and x < 60:
    print('You are not that young, but not that old also!')
elif x > 60 and x < 100:
    print ('Golden ages!')
elif x < 0 or x > 100:
    print ('I do not really believe you that you are younger than 0 or older than 100!')
else:
    print ('Invalid selection.')

The code above will check the user input and print the corresponding message. For example, if the user enters the value of 45, the elif x > 40 and x < 60 statement will evaluate to True and the You are not that young, but not that old also! message will be printed.

Here is the output:

Enter your age: 58
You are not that young, but not that old also!
>>> 
Enter your age: 12
Oww, you are still a child!
>>> 
Enter your age: 105
I do not really believe you that you are younger than 0 or older than 100!
>>> 
Enter your age: -6
I do not really believe you that you are younger than 0 or older than 100!
>>> 
Enter your age: 25
You are so young!
>>> 
Enter your age: 68
Golden ages!