2D ARRAY (MATRIX) - Segmentation Fault (CORE DUMPED)

Question

I have created the following program which takes user's input of an nxn array and prints it. My code has three functions namely for memory allocation for a 2D array, user data input and displaying stored data. While 1x1 to 4x4 matrix works fine, 5x5 and above matrix results in

    Segmentation fault (core dumped)

Why is it so? What am I doing wrong ? The following is my code-

#include <stdio.h>
#include <stdlib.h>

int ** allocateMemory(int, int);
void createMatrix(int **, int, int);
void displayMatrix(int **, int, int);

int main()
{
  int sizeA, sizeB;

  printf("\nMatrix type(a x b): ");
  scanf("%d %d", &sizeA, &sizeB);
  printf("You entered: %d x %d\n", sizeA, sizeB);
  int ** arrayA;

  arrayA = allocateMemory(sizeA, sizeB);
  printf("\nMATRIX A\n");
  createMatrix(arrayA, sizeA, sizeB);
  displayMatrix(arrayA, sizeA, sizeB);

  getchar();
  free(arrayA);
  printf("\n");
  return 0;
}

/*-----------------------------------------*/
/* FUNCTION TO ALLOCATE MEMORY TO AN ARRAY */
/*-----------------------------------------*/

int ** allocateMemory(int r, int c)          //r - rows, c - columns
{
  int ** ptr;
  ptr = (int **) malloc(r*sizeof(int));
  for(int i = 0; i < r; i++){
    ptr[i] = (int *) malloc(c*sizeof(int));
  }
  return ptr;
}

/*-----------------------------*/
/* FUNCTION TO CREATE A MATRIX */
/*-----------------------------*/

void createMatrix(int ** array, int r, int c)
{
  printf("\nEnter matrix values: \n");
  for(int i = 0; i < r; i++){
    for(int j = 0; j < c; j++){
      scanf("%d", &array[i][j]);
    }
  }
  printf("Array Created.");
  printf("\n");
}

/*----------------------------*/
/* FUNCTION TO DISPLAY MATRIX */
/*----------------------------*/

void displayMatrix(int ** array, int r, int c)
{
  printf("\n");
  for(int i = 0; i < r; i++){
    for(int j = 0; j < c; j++){
      printf("%5d  ", *(*(array + i) + j));
    }
    printf("\n");
  }
}

Answer 1

In allocateMemory() you have

ptr = (int **) malloc(r*sizeof(int));

That line is wrong, because you want t allocate memory for an array of pointers, so it shoud be

ptr = malloc(r*sizeof(int *));

or

ptr = malloc(r*sizeof *ptr);

If sizeof(int) < sizeof(int *) (as it is in general on 64bit platforms) you don't allocate enough memory which invokes Undefined Behaviour. And "Undefined" means that anything might happen, including that the codes seems to run flawlessly (at least for certain values of r and c in your case)

Off topic:

you might to want to read about why you should not cast the result of malloc()