char *strStr(char *haystack, char*needle)

      {

          char* p1;

          char* p2;

          char* p1_advance=haystack;

          //当字符串数量不足时，直接停止匹配

          for (p2 = &needle[]; *p2; p2++)

              p1_advance++;

          for (p1 = haystack; *p1_advance; p1_advance++)

          {

              char *p1_old = p1;

              p2 = needle;

              while (*p1 && *p2 && *p1 == *p2)

              {

                  p1++;

                  p2++;

              }

              if (!*p2)return p1_old;

              p1 = p1_old + ;

          }

          return nullptr;

      }