𝑓(𝑥) = −1，x＜0；

𝑓(𝑥) = 0，x=0；

𝑓(𝑥) = 1，x＞0；

#include <stdio.h>
int main()
{
	int x,y;

	printf("Enter two integers: ");
	scanf_s("%d", &x);

	if(x > 0)
	{
		y = 1;
		printf("x=%d y=%d\n",x,y);
	}
	else if(x == 0)
		{
			y = 0;
			printf("x=%d y=%d\n",x,y);
		}
		else
		{
			y = -1;
			printf("x=%d y=%d\n",x,y);
		}
	
	return 0;
}