Simple Password Checker

[deanhystad]

Since people are submitting solutions now, I thought I might demonstrate a different approach. This is a pass/fail implementation with feedback. Get comfortable with Python exceptions. They are very useful.

def set_password(password):
    if len(password) < 7:
        raise ValueError("Password must be at least 7 characters")

    if not any(map(str.islower, password)):
        raise ValueError("Password must contain a lowercase letter")

    if not any(map(str.isupper, password)):
        raise ValueError("Password must contain an uppercase letter")

    if not any(map(str.isdigit, password)):
        raise ValueError("Password must contain a digit")

    if not (set(password) & set('!@#$%^&*()')):
        raise ValueError("Password must contain a special character")

    # Code that sets the password goes here

while password := input('Enter New Password: '):
    try:
        set_password(password)
        break
    except ValueError as msg:
        print(msg)

This computes a strength score.

def password_strength(password):
    strength = 0 if len(password) < 7 else 1

    if any(map(str.islower, password)):
        strength += 1

    if any(map(str.isupper, password)):
        strength += 1

    if any(map(str.isdigit, password)):
        strength += 1

    if set(password) & set('!@#$%^&*()'):
        strength += 1

    return strength

while password := input('Enter New Password: '):
    print(password_strength(password))

And if you love unreadable one-liners:

def valid_password(p):
    return all([len(p) > 0, any(map(str.islower, p)), any(map(str.isupper, p)), any(map(str.isdigit, p)), set(p) & set('!@#$%^&*()')])

while password := input('Enter New Password: '):
    print(valid_password(password))

It is good to know about any() and all(). To use any() or all() affectively it is also good to know about map() and list comprehensions.