#include <stdio.h>

struct foo
{
	int a;
	int b;
};

void swap(struct foo input)
{
	int tmp = input.a;
	input.a = input.b;
	input.b = tmp;
}

int main( void )
{
	struct foo first;
	first.a = 1;
	first.b = 2;
	printf("before swap first.a = %d\n",first.a);
	printf("before swap first.b = %d\n",first.b);
	swap(first);

	printf("after swap first.a = %d\n",first.a);
	printf("after swap first.b = %d\n",first.b);

return 0;
}

/*
before swap first.a = 1
before swap first.b = 2
after swap first.a = 1
after swap first.b = 2
*/