#include <stdio.h>
#define  DIFF_ABS(X, Y)     ( (x)>(y) ? (x)-(y) : (y)-(x) )

int main(void)
{
	printf("두 값의 차: %d \n", DIFF_ABS(5, 7));
	printf("두 값의 차: %g \n", DIFF_ABS(1.8, -1.4));
	return 0;
}

In function 'main':
Line 6: error: 'x' undeclared (first use in this function)
Line 6: error: (Each undeclared identifier is reported only once
Line 6: error: for each function it appears in.)
Line 6: error: 'y' undeclared (first use in this function)