#include <stdio.h>
#include <assert.h>
#include <string.h>

char* my_strcpy1(char* dest, const char* src)
{
        assert(dest != NULL && src != NULL);
        char* ret = dest;
        while((*dest++ = *src++) != ‘\0‘);
        return ret;                  
}
//较第一种效率
char* my_strcpy2(char* dest, const char* src)
{
    assert(dest != NULL && src != NULL);
    char* s = (char*) src;
    int delt = dest - src;
    while((s[delt] = *s++) != ‘\0‘);
    return dest;                  
}

int main(void)
{
        char str1[4];
        char str2[4];
        char str3[4];  
   
        strcpy(str1,"sam");
        my_strcpy1(str2,"sam");
        my_strcpy2(str3,"sam");
  
        printf("str1 = %s\n", str1);
        printf("str1 = %s\n", str2);
        printf("str1 = %s\n", str3);

    return 0;  
}