Thread: cant free my memory

hello ,i need some help with free memory
my allocation:
(pixel is struct of RGB)

Code:

pixel** array(int Y, int X) {
    pixel** theArray;
    theArray = (pixel**)malloc(Y * sizeof(pixel*));
    for (int i = 0; i < Y; i++) {
        theArray[i] = (pixel*)malloc(X * sizeof(pixel));
    }
    return theArray;

Code:

void freeMatrix(pixel ** pmatrix, size_t rows){            for (int i = 0; i < rows; ++i)
            {
                free((pmatrix)[i]);\\problem is here
            }
        free(pmatrix);
        pmatrix = NULL;
    }

what am i doing wrong ?

Originally Posted by john.c

pmatrix needs to be a triple pointer to be able to set it to NULL in the caller.

Code:

void freeMatrix(pixel *** pmatrix, size_t rows){
    for (int i = 0; i < rows; ++i)
        free((*pmatrix)[i]);
    free(*pmatrix);
    *pmatrix = NULL;
}

However, a better way to allocate a 2-d array is like this:

Code:

pixel** matrix_new(int rows, int cols) {
    pixel** m = malloc(rows * sizeof *m);   // allocate row pointers
    m[0] = calloc(rows * cols, sizeof **m); // allocate data block
    for (int i = 1; i < rows; ++i)          // set row pointers
        m[i] = m[i - 1] + cols;
    return m;
}
 
void matrix_delete(pixel*** m) {
    free((*m)[0]);  // delete data block
    free(*m);       // delete row pointers
    *m = NULL;
}

i tried to free with the first function and its stiil doesnt work.
you know what is the problem?