编辑代码

#include <stdio.h>
char *strcopy(char* dest,char *src){
    if(dest==NULL||src==NULL)return NULL;
    if(dest==src)return dest;
    char *out=dest;
    while(*dest++=*src++);
    return out;
}
int main () {
    char a[]="abcde";
    strcopy(a," 2");
    printf("%s\n",a);
    printf("%d\n",strlen(a));
	return 0;
}