C语言实现strcpy

 1 #ifndef STRCPY_H
 2 #define STRCPY_H
 3 
 4 #include <stdio.h>
 5 
 6 char *cat_strcpy(char *dst, const char *src) {
 7     if (NULL == src || NULL == src)
 8         return NULL;
 9 
10     char *s = (char *)src, *d = dst;
11 
12     while ((*d++ = *s++) != ‘\0‘) {
13         // do nothing
14     }
15     *d = ‘\0‘;
16 
17     return dst;
18 }
19 
20 #endif

 1
 2 #include "strcpy.h"
 3 
 4 
 5 void test_strcpy();
 6 
 7 int main() {
 8     test_strcpy();
 9 
10     return 0;
11 }
12 
13 
14 void test_strcpy() {
15     char *src = "test_strcpy";
16     char dest[20] = { 0 };
17     cat_strcpy(dest, src);
18 
19     printf("%s\n", dest);
20 }

int length = strlen(strcpy(str1,str2));