C语言中使用struct实现数组复制

在C语言中，直接在参数中声明数组变量是无法实现传值传参的，这时只会把数组的首地址传过去。将数组放置到一个struct中进行传参，可以实现传值的方式。例如下面的程序：

#include <stdio.h>

struct tag {int a[100]};
struct tag orange, lime, lemon;

struct tag twofold(struct tag s){
	int i;
	for(i=0; i<100; i++){
		s.a[i] *= 2;
	}
	return s;
}

int main(){
	int i;
	for(i=0; i<100; i++){ orange.a[i] = 1; }
	lime = twofold(orange);
	for(i=0; i<10; i++){
		printf("before: lime.a[%d] = %d\n", i, lime.a[i]);
	}
	lemon = lime;
	for(i=0; i<100; i++){ lemon.a[i] = 7; }	

	for(i=0; i<10; i++){
		printf("lemon.a[%d] = %d\n", i, lemon.a[i]);
	}

	for(i=0; i<10; i++){
		printf("after: lime.a[%d] = %d\n", i, lime.a[i]);
	}
}

输出结果：

before: lime.a[0] = 2
before: lime.a[1] = 2
before: lime.a[2] = 2
before: lime.a[3] = 2
before: lime.a[4] = 2
before: lime.a[5] = 2
before: lime.a[6] = 2
before: lime.a[7] = 2
before: lime.a[8] = 2
before: lime.a[9] = 2
lemon.a[0] = 7
lemon.a[1] = 7
lemon.a[2] = 7
lemon.a[3] = 7
lemon.a[4] = 7
lemon.a[5] = 7
lemon.a[6] = 7
lemon.a[7] = 7
lemon.a[8] = 7
lemon.a[9] = 7
after: lime.a[0] = 2
after: lime.a[1] = 2
after: lime.a[2] = 2
after: lime.a[3] = 2
after: lime.a[4] = 2
after: lime.a[5] = 2
after: lime.a[6] = 2
after: lime.a[7] = 2
after: lime.a[8] = 2
after: lime.a[9] = 2

参考《C专家编程》