参考方法：

#include<stdio.h>
#include<string.h>
int fun(char *a,char *b)
{
  int count = 0;
  char *p;
  int len_b = strlen(b);
  while((p = strstr(a,b)) != NULL)
  {
    count++;
    a = p + len_b;
  }
  return count;
}
int main()
{
  printf("%d\n",fun("dh123dhgfdgsshdhscnbdh","dh"));
  return 0;
}