为什么自己的copy函数没输出

Question

#include<stdio.h>
int main()
{
	  void copy(char*, char*);   
	char* a = "i am a knight";
	char* b = "or be  guilty";
	printf("a=%s   b=%s\n", a, b); //初始化并输出字符指针
	printf("把a赋给b\n");
	copy(a, b);                    //将前一个字符串覆盖后一个
    printf("a=%s   b=%s",a,b);
    return 0;	
}
void copy(char*s,char *d)
{
	while ((*d++ = *s++) != '\0');    
}

调试进入函数显示

 

Answer 1

可以把

char* a = "i am a knight";

char* b = "or be guilty";

改成

char a[] = "i am a knight";

char b[] = "or be guilty";