malloc，free实验

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

int main()
{
  char a = 0;
  //int * p = (int * ) malloc (4 * sizeof(int));
  int * p = (int * ) malloc (4);
  char * cp = (char * ) malloc (4 * sizeof(char));

  a = 1;
  a = (char)(~0);
  a = 0;
  a |= (~((~0)<<5) <<3);

  //step-by-step program
  a = 0;
  a = (char)(~0);
  a = a << 5;
  a = ~a;
  a = a << 3;

  if(NULL == p)
  {
    printf("malloc failed\n");
    return -1;
  }

  if(NULL == cp)
  {
    printf("malloc failed\n");
    return -1;
  }

  *(p+0) = 1;
  *(p+1) = 3;
  *(p+2) = 5;
  *(p+3) = 4;
  *(cp+0) = 1;
  *(cp+1) = 3;
  *(cp+2) = 5;
  *(cp+3) = 4;
  //*(p+4) = 6; //编译通过，但无法运行。
  printf("%d\n", *(p+3));

  free (p);

  free (cp);

  return 0;
}