Thread: Comparing "Struct Char" with "Char in Char Array"

Just making a program to optimize a game I encountered, which is why I didn't put much thought into it.

For some reason I cannot compare a char in a struct and a char in a char array together (one of them is a pointer?)

I get the error:
C:\Users\Unknown\Desktop\5X5 Word Game\main.cpp|71|error: ISO C++ forbids comparison between pointer and integer|

Thanks!

Code:

#include <iostream>
#include <fstream>
#include <stdlib.h>

using namespace std;

struct single
{
    char letter;
    bool players;
};

int main()
{
    int numWords = 160000;
    int maxLength = 100;

    char **words = new char*[numWords];
    words[0] = new char[numWords*maxLength];
    for ( int i = 1 ; i < numWords ; i++)
    {
        words[i] = words[i-1] + maxLength;
    }

    //Essentially: words[160000][100]


    ifstream ifs("en-US.dic", ios::in);

    for(int a = 0; a<numWords; a++)
    {
        ifs >> words[a];
        //cout << words[a] << endl;
    }

    single Grid[25];
    single tempGrid[25];

    for(int a = 0; a<25; a++)
    {
        Grid[a].letter = 0;
        Grid[a].players = false;
    }

    string tempAllLetters;

    cout << "Enter all letters: ";
    cin >> tempAllLetters;

    for(int b = 0; b<25; b++)
    {
        Grid[b].letter = tempAllLetters[b];
    }


    bool check;

    for(int a = 0; a<numWords; a++) //each cycle checks if each word is possible
    {
        for(int b = 0; b<25; b++)
        {
            tempGrid[b].letter = Grid[b].letter;
        }

        for(int b = 0; b<25; b++)
        {
            check = false;

            for(int c = 0; c<25; c++)
            {
                if(words[b] == tempGrid[c].letter && words[b] != 0)
                {
//                    check = true;
//                    tempGrid[c].letter = 0;
//                    tempGrid[c].players = true;
                }
            }

            if(check == false)
            {
                break;
            }

        }

    }

    return 0;
}

Code:

if(words[b] == tempGrid[c].letter && words[b] != 0)

Well words is a char**, so words[b] is a char*. On the other hand, tempGrid[c].letter is a char. You can't compare a char* directly to a char, and that's what the compiler is complaining about.

To check whether two char*'s are the same, use strcmp(); to see whether a char is inside a string (word) use strchr(). You could also be using the standard std::string class to make your life easier.

This is horrible C code with some C++ mixed in. You need to fix this before moving on.
First off, stop using char arrays. Stop. Forget they exist. For strings, use std::string. Include <string>. Now it's completely natural. No strcmp, no new.
Don't use dynamic 2D C arrays. Stop. Forget they exist. If you need a 2D array, you can use the slightly convulsed syntax:

std::vector<std::vector<T>> v(N, std::vector<T>(M));

To more easily understand what it means, you could think of it in the following way:

T v[N][M];

(They are not the same; but it gives you an idea of what it does.)
In your case, however, you do not need a 2D array. You need a 1D array of strings, so:

std::vector<std::string> v(size);

Better yet, since the number of words are fixed, you could do

std::array<std::string, size> words;

If you really need a dynamic array (ie, an array whose size changes over time, or whose size is determined at runtime), you could simply do

std::vector<std::string> words;
//...
words.push_back("my string");

The container will automatically expand as it needs more room to store your strings.
They also do not require you to call delete as you need in your current code (which currently leaks memory - which is very bad!).

I don't know what the rest of your code does. Though, I presume it searches through a file for matches on a word or some string of letters.
You are much better of using stream iterators (http://en.cppreference.com/w/cpp/ite...tream_iterator) or just reading line-by-line (std::getline). You save tons of memory and much complexity.

std::vector requires you to include <vector>.
std::array requires you to include <array>.