C Language Implementation strcpy

Strcpy.h:

1 #ifndef Strcpy_h2 #defineStrcpy_h3 4#include <stdio.h>5 6 Char*cat_strcpy (Char*DST,Const Char*src) {7     if(NULL = = SRC | | NULL = =src)8         returnNULL;9 Ten     Char*s = (Char*) src, *d =DST; One  A      while((*d++ = *s++)! =' /') { -         // do nothing -     } the*d =' /'; -  -     returnDST; - } +  - #endif

Main

12#include"Strcpy.h"3 4 5 voidtest_strcpy ();6 7 intMain () {8 test_strcpy ();9 Ten     return 0; One } A  -  - voidtest_strcpy () { the     Char*SRC ="test_strcpy"; -     Chardest[ -] = {0 }; - cat_strcpy (dest, SRC); -  +printf"%s\n", dest); -}

strcpy (STR1,STR2) function can copy content from str2 to str1, Why do I need function return value ? It should be easy to implement chain expressions, such as:

int length = strlen (strcpy (STR1,STR2));

C Language Implementation strcpy