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;
}

参考方法：

#include <stdio.h>
#include <string.h>
int strCount(char strM[], char strS[]);

int main()
{
   char strM[100], strS[100];
   printf("请输入两个字符串，以回车隔开，母串在前，子串在后：\n");
   scanf("%s\n%s", strM, strS);
   printf("%d", strCount(strM, strS));
}

int strCount(char strM[], char strS[])
{
   int count = 0, m;
   for (int i = 0; i < strlen(strM); ++i)//strlen返回无符号整型数
   {
      m = i;
      char *Mp = &strM[m], *Sp = strS;//子串从开头开始，母串从当前位置开始
      while (*Sp != '\0')
      {
         if (strM[m++] != *Sp++) break;
         if (*Sp == '\0') ++count;
      }
   }
   return count;
}