2D array is used uninitialized in this function

Question

I'm getting a warning:

matrixResult' is used uninitialized in this function [-Wuninitialized]

in this function:

int **addMatrices(int **matrixA, int **matrixB, int *rows, int *cols) {
    int **matrixResult = initializeMatrix(matrixResult, rows, cols);
    for (int i = 0; i < *rows; i++)
        for (int j = 0; j < *cols; j++)
            matrixResult[i][j] = matrixA[i][j] + matrixB[i][j];

    return matrixResult;
}

But its is getting initialized here:

int **initializeMatrix(int **matrix, int *rows, int *cols) {
    matrix = (int **)malloc((*rows) * sizeof(int*));
    checkNullPointer(matrix);
    for(int i = 0; i < *rows; i++) {
        matrix[i] = (int *)calloc(*cols, sizeof(int));
    }

    return matrix;
}

isn't it? I was trying to find an answer, but everyone just says that 2D array needs to get allocated . But I think that it gets in my code. Anyone has a clue what's going on in here?

Answer 1

You have passed the uninitialised pointer, unnecessarily, and used it as a local variable. If you remove that and use a true local variable, like this:

int **initializeMatrix(int *rows, int *cols) {
    int **matrix = malloc((*rows) * sizeof(int*));
    checkNullPointer(matrix);
    for(int i = 0; i < *rows; i++) {
        matrix[i] = calloc(*cols, sizeof(int));
    }

    return matrix;
}

int **addMatrices(int **matrixA, int **matrixB, int *rows, int *cols) {
    int **matrixResult = initializeMatrix(rows, cols);
    for (int i = 0; i < *rows; i++)
        for (int j = 0; j < *cols; j++)
            matrixResult[i][j] = matrixA[i][j] + matrixB[i][j];

    return matrixResult;
}

then the warning should go away.

Aside: I also removed the unnecessary casts.