Bool fonction never returns FALSE... why?

I am stuck on CS50 week 2 password problem.
I have figured out most of it, but no matter what I input, the return is always TRUE.

What am I missing?

// TODO: Complete the Boolean function below
bool valid(string password)
{

int validation;
validation = 0;

//find length of string (password)

for (int n = 0; n < strlen(password); n++)

//conditions to achieve for the bool to be true

 {
    if (isupper(password[n]))
     {
         validation = validation + 1;
     }

    if (islower(password[n]))
     {
          validation = validation + 1;
     }

    if (ispunct(password[n]))
     {
         validation = validation + 1;
     }

   if (isdigit(password[n]))
     {
          validation = validation + 1;
     }
 }
   if (validation == 4)
    {
        return true;
    }
   else
   {
        return false;
   }

}

You're incrementing validation every time one of the conditions is met, but the conditions may be met by multiple characters in the password.

In fact, if the password contains only characters that are an uppercase letter, a lowercase letter, a number, or a punctuation character (pretty much anything except a space!) then you'll increment validation once for each character, so validation will equal the length of the password.

Consider an input TEST: each character matches the uppercase condition, so validation is incremented 4 times, so the final validation == 4, which then returns true, even though it didn't satisfy all the conditions.

Then consider a different input Test1!:

• first character T is uppercase, so validation += 1 => 1
• second character e is lowercase, so validation += 1 => 2
• third character s is lowercase, so validation += 1 => 3
• fourth character t is lowercase, so validation += 1 => 4
• fifth character 1 is a number, so validation += 1 => 5
• sixth character ! is punctuation, so validation += 1 => 6

... which then returns false.

The problem is that it's allowing each satisfied condition multiple times. Your working code will need to consider each condition separately.