strstr函数内部实现

#include <stdio.h>
#include <string.h>
#include <assert.h>

char* my_strstr(const char* str1, const char* str2)
{
    assert(str1 && sttr2);
    const char* s1 = str1;
    const char* s2 = str2;
    const char* p = str1;//第二次始的字符串放到指针变量p中
    while (*p)//从源字符串中查找 遇到\0结束
    {
        s1 = p;
        s2 = str2;
        while (*s1 != '\0' && *s2 != '\0' && *s1 == *s2)
        {
            s1++;
            s2++;
        }
      if (*s2 == '\0')
      {
          return (char*)p;
      }
      p++;
    }
    return NULL;
}

int main()
{
    char arr1[] = "asdagffhhjk";
    char arr2[] = "fh";
    char* srt = my_strstr(arr1,arr2);
    if (srt == NULL)
        printf("wu\n");
    else
    printf("%s\n",srt);//fhhjk
    return 0；
}

该函数是查找函数，从str1字符串中找str2字符串。