Heap Memory Example

For the execution of this program fragment:

int *p, *arr;
char *c_arr;

p = (int *)malloc(sizeof(int));
arr = (int *)malloc(sizeof(int)*20);
c_arr = (char *)malloc(sizeof(char)*10);

if((p == NULL) || (arr == NULL) || (c_arr == NULL)) {
   printf("malloc error\n");
   exit(1);
}

*p = 6;
*arr = 8;
arr[3] = 10;
strcpy(c_arr, "He");
c_arr[1] = 'i';

The contents of memory will look like this:

            STACK                                    HEAP

      |===============|                |====================================|
main: |               |                |                                    |
      |       ----    |                |    ----                            |
      |    p | *-------------------------->| 6 |                            |
      |       ----    |                |    ----                            |
      |      ----     |                |    -------------------------       |
      |  arr | *-------------------------->| 8 | ? | ? | 10 | ? |...|       |
      |      ----     |                |    -------------------------       |
      |       ----    |                |    -------------------------       |
      | c_arr | *-------------------------->| 'H' | 'i' | '\0' | ...|       | 
      |       ----    |                |    -------------------------       |
      |===============|                |====================================|