Strcpy是个很难写的函数

 char * p = "0123456789abcdefghijklmn";
 char buf[1024];
 char * p1 = buf;
 char * p2 = buf + 10;

 memset(buf, 0, 1024);
 strcpy(p1, p);
 strcpy(p1, p2);
 strcpy(p1, 0);
　　……