CODEWITHSUNDEEP
arrayscc-stringsreturn-type
Aignessan
Aignessan

Reputation: 9

incompatible return type when attempting to return 2d array in c

I'm attempting to write a function that returns a 2 dimensional array. This code is supposed to return a list with the absolute paths of the input files.

char** findFiles(char rawFileList[100][1000], int numFiles) {
    char (*absolutepaths)[1000] = malloc(1000 * sizeof(*absolutepaths)); 

    int count1 = 0;

    int files = numFiles; //unused

    while (count1 < numFiles) {
        if ((is_file(rawFileList[count1])) != 0) { 
            char *path = realpath(rawFileList[count1], NULL);
            strcpy(absolutepaths[count1], path);
        } else { //it is d
            listFilesRecursively(absolutepaths[count1]);
        }
        count1++;
    }
    printf("%s", absolutepaths[1]);

    return absolutepaths;
}

But I'm getting this error message:

error: returning ‘char (*)[1000]’ from a function with incompatible return type ‘char **’ [-Werror=incompatible-pointer-types]
   68 | return absolutepaths;

I tried to resolve this issue but I have only drawn blanks so far. Any advice or help anyone can offer would be much appreciated.

Upvotes: 1

Views: 113

Answers (1)

0___________
0___________

Reputation: 67526

It is quite common (not only for beginners) misunderstanding.

** pointers are not 2D arrays or pointers to arrays.

You need to return a pointer to the array or (if the size of the array is not known or passed as a parameter a pointer to void

int (*functionReturnninPointerToArray(int array[][100]))[100]
{
    /* .... */
    return array;
}

void* functionReturnninPointerToVLA(size_t cols, int array[][cols])
{
    /* .... */
    return array;
}

The first one can be also written as

typedef int array100[100];

array100 *functionReturnninPointerToArray(array100 *array)
{
    /* .... */
    return array;
}

Upvotes: 2

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