c语言中i++与++i区别

#include<stdio.h>
int main(void)
{
	int i=5,y;
	y=i++*++i;
	printf("i=%d\n",i);
	printf("y=%d\n",y);

	i=5;
	y=i++*i++;
	printf("i=%d\n",i);
	printf("y=%d\n",y);

	return 0;
}