void revers(char *buf){
  char *p = buf;
  if (p == NULL) {

    return;
  }
  //遞歸結(jié)束條件
  if (*p == '\0') {

    return;
  }
  //遞歸調(diào)用
  revers(p + 1);
  //在字符串的結(jié)尾追加n個字符
  strncat(buf_g, p, 1);




}

int main(int argc, const char * argv[]) {

  char *c = "abcde";
  //清空
  memset(buf_g, 0, sizeof(buf_g));

  revers(c);
  printf("%s\n",buf_g);



  return 0;
}