Python Exercise: Check the validity of a password

Last update on March 26 2025 08:11:54 (UTC/GMT +8 hours)

15. Password Validity Checker

Write a Python program to check the validity of passwords input by users.

Validation :

• At least 1 letter between [a-z] and 1 letter between [A-Z].
• At least 1 number between [0-9].
• At least 1 character from [$#@].
• Minimum length 6 characters.
• Maximum length 16 characters.

Sample Solution:-

Python Code:

# Import the 're' module for regular expressions
import re

# Prompt the user to input a password and store it in the variable 'p'
p = input("Input your password")

# Set 'x' to True to enter the while loop
x = True

# Start a while loop that continues until 'x' is True
while x:  
    # Check conditions for a valid password:
    # Password length should be between 6 and 12 characters
    if (len(p) < 6 or len(p) > 12):
        break
    # Password should contain at least one lowercase letter
    elif not re.search("[a-z]", p):
        break
    # Password should contain at least one digit
    elif not re.search("[0-9]", p):
        break
    # Password should contain at least one uppercase letter
    elif not re.search("[A-Z]", p):
        break
    # Password should contain at least one special character among '$', '#', '@'
    elif not re.search("[$#@]", p):
        break
    # Password should not contain any whitespace character
    elif re.search("\s", p):
        break
    else:
        # If all conditions are met, print "Valid Password" and set 'x' to False to exit the loop
        print("Valid Password")
        x = False
        break

# If 'x' remains True, print "Not a Valid Password"
if x:
    print("Not a Valid Password")

Sample Output:

Input your passwordW3r@100a                                                                                   
Valid Password 

Flowchart:

For more Practice: Solve these Related Problems:

• Write a Python program to validate a password ensuring it has at least one lowercase, one uppercase, one digit, and one special character, with length constraints.
• Write a Python program to prompt the user for a password and check it against a set of complexity rules, outputting validation errors.
• Write a Python program to use regular expressions to verify that an input string meets password criteria including mixed cases and digits.
• Write a Python program to implement a password checker that returns True only if the password satisfies all given rules, otherwise False.

Python Code Editor:

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