Input validation not functioning

Question

I am trying to parse input from a file to represent a standard deck of cards (i.e. 2C represents the two of clubs). However, my solution is not working as expected, and is declaring all inputs to be invalid. I can't see any logical errors in my code, so I wanted to get a second opinion. The code is below:

/*
 * Determines if the input string is valid.
 * 
 * A string is considered valid if it begins with either a number (2-10) 
 * or a letter (J/j, Q/q, K/k) to deetermine rank, followed by a letter to
 * determine suit (C/c, D/d, H/h, S/s).
 */
bool inputValidator(string cardData)
{
    if (cardData.length() == 2) //Input string is two characters long
    {
        if (cardData[0] < '2' || cardData[0] > '9'
            || cardData[0] != 'J' || cardData[0] != 'j'
            || cardData[0] != 'Q' || cardData[0] != 'q'
            || cardData[0] != 'K' || cardData[0] != 'k'
            || cardData[0] != 'A' || cardData[0] != 'a')
        {
            cout << "Card with data " << cardData << " has an invalid rank." << endl;
            return false;
        }
        if (cardData[1] != 'C' || cardData[1] != 'c' //Parse suit
            || cardData[1] != 'D' || cardData[1] != 'd'
            || cardData[1] != 'H' || cardData[1] != 'h'
            || cardData[1] != 'S' || cardData[1] != 's')
        {
            cout << "Card with data " << cardData << " has an invalid suit." << endl;
            return false;
        }
        return true;
    }
    else if (cardData.length() == 3) //Input string is three characters long
        //This occurs only if the number is 10.
    {
        if (cardData[0] != '1' || cardData[1] != '0') //Parse rank
        {
            cout << "Card with data " << cardData << " has an invalid rank." << endl;
            return false;
        }
        if (cardData[2] != 'C' || cardData[2] != 'c' //Parse suit
            || cardData[2] != 'D' || cardData[2] != 'd'
            || cardData[2] != 'H' || cardData[2] != 'h'
            || cardData[2] != 'S' || cardData[2] != 's')
        {
            cout << "Card with data " << cardData << " has an invalid suit." << endl;
            return false;
        }
        return true;
    }
    return false;
}

If there are any logical flaws (or an inherently better way to do this), I would appreciate being told. Thanks.

Answer 1

Your logic expression isn't correct, also you are duplicating code, try to simply them to functions.

bool inputValidator(string cardData)
{
    if (cardData.length() == 2 && IsValidCard(cardData[0])) //Input string is two characters long
    {
        return IsValidSuite(cardData[1]);
    }
    else if(cardData.length() == 3) 
    {
        if (isValidRank(cardData[0]))
        {
            return IsValidSuite(cardData[2]);
        }
    }
    return false;
}

bool isValidRank(char c)
{
    if (c =='0' || c=='1')[
    {
        return true;
    }
    return false;
}

bool IsValidCard(char c)
{
  if (c > '2' && c < '9')
  {
    return true;
  }

  switch(c)
  {
    case 'J':
    case 'j':
    case 'Q':
    case 'q':
    case 'K':
    case 'k':
    case 'A':
    case 'a':
      return true;
  }

  return false;
}    

bool IsValidSuite(char c)
{
  switch(c)
  {
    case 'C':
    case 'c':
    case 'D':
    case 'd':
    case 'H':
    case 'h':
    case 'S':
    case 's':
      return true;
  }
  return false;
}

Answer 2

You can simplify the conditions a bit: And your conditions must be changed to do what you want.

bool inputValidator(string cardData)
{
    if (cardData.length() == 2) //Input string is two characters long

   {
        if (!((cardData[0] >= '2' && cardData[0] <= '9')
            || (cardData[0]|32) == 'j'
            || (cardData[0]|32) == 'q'
            || (cardData[0]|32) == 'k'
            || (cardData[0]|32) == 'a'))
        {
           cout << "Card with data " << cardData << " has an invalid rank." << endl;
           return false;
         }

        if (!((cardData[1]|32) == 'c' //Parse suit
            || (cardData[1]|32) == 'd'
            || (cardData[1]|32) == 'h'
            || (cardData[1]|32) == 's'))
        {
            cout << "Card with data " << cardData << " has an invalid suit." << endl;
            return false;
        }
        return true;
    }
    else if (cardData.length() == 3) //Input string is three characters long
        //This occurs only if the number is 10.
    {
        if (!(cardData[0] == '1' || cardData[1] == '0')) //Parse rank
        {
            cout << "Card with data " << cardData << " has an invalid rank." << endl;
            return false;
        }
        if (!((cardData[2]|32) == 'C' //Parse suit
            || (cardData[2]|32)  == 'd'
            || (cardData[2]|32)  == 'h'
            || (cardData[2]|32)  == 's'))
        {
            cout << "Card with data " << cardData << " has an invalid suit." << endl;
            return false;
        }
        return true;
    }
    return false;
}

The code duplication for the second / third character should also be refactored.

Answer 3

You're writing clauses like this:

cardData[2] != 'D' || cardData[2] != 'd'

Which will always be true, as the variable being tested can't be both values at the same time. You probably meant to use && rather than ||.

You could certainly simplify the logic, for example by converting the input to lower or upper case before comparing it.

Answer 4

The problem seems to be in the way you combine your conditions. If I understand your expectation correctly, what you want for the first conditions is this:

    if (!(cardData[0] > '2' && cardData[0] < '9')
        && cardData[0] != 'J' && cardData[0] != 'j'
        && cardData[0] != 'Q' && cardData[0] != 'q'
        && cardData[0] != 'K' && cardData[0] != 'k'
        && cardData[0] != 'A' && cardData[0] != 'a')

And what you want for the second condition is this:

    if (cardData[1] != 'C' && cardData[1] != 'c' //Parse suit
        && cardData[1] != 'D' && cardData[1] != 'd'
        && cardData[1] != 'H' && cardData[1] != 'h'
        && cardData[1] != 'S' && cardData[1] != 's')