模拟库函数strstr

#include
#include


char* my_strstr(const char* str1,const char* str2)
{
  
  char *cur=(char*)str1;
  char *p1=NULL;
  char *p2=NULL;
  

  if(*str1=='\0')
    return (char*)str1;
  while(*cur)
  {
    p1=cur;
    p2=(char*)str2;

    while(*p1!='\0' && *p2!='\0' && (*p1==*p2))
    {
      p1++;
      p2++;
    }
    if(*p2=='\0')
      return cur;
        if(*p1=='\0')
            return NULL;
        
    cur++;

  }
  return NULL;//找不到子串
}
int main()
{
  char *str1="abcdef";
  char *str2="def";

  char* ret=my_strstr(str1,str2);

  if(ret==NULL)
  {
    printf("子串不存在\n");
  }
  else
  {
    printf("%s\n",ret);
  }
  
}