C言語 INFINITYの比較

すごく当たり前だけどメモ。

# include <stdio.h>
# include <math.h>

int main()
{
	double n = INFINITY;
	double inf = INFINITY;

	printf("%4f  < %4f is %d\n", n, inf, n < inf);
	printf("%4f  > %4f is %d\n", n, inf, n > inf);
	printf("%4f  < %4f is %d\n", -n, inf, -n < inf);
	printf("%4f  < %4f is %d\n", n, -inf, n < -inf);
	printf("%4f  < %4f is %d\n", -n, -inf, -n < -inf);
	printf("%4f == %4f is %d\n", n, inf, n == inf);
	printf("%4f == %4f is %d\n", -n, inf, -n == inf);
	printf("%4f == %4f is %d\n", -n, -inf, -n == -inf);
	return (0);
}

 inf  <  inf is 0
 inf  >  inf is 0
-inf  <  inf is 1
 inf  < -inf is 0
-inf  < -inf is 0
 inf ==  inf is 1
-inf ==  inf is 0
-inf == -inf is 1