#include <stdio.h>
#include <assert.h>
char *str_copy(char *des, const char *src)
{
assert(src != NULL);
assert(des != NULL);
while ((*des++ = *src++) != '\0');
return des;
}
int main()
{
const char *src = "chenyu";
char des[100];
str_copy(des, src);
puts(des);
}