examples: how to compare float number in Clang.

floatCompare.c

#include<stdio.h>

main()
{
	float i=7, j=10, k=0.7;
	const float EPSILON = 0.000000000000000001;
	//const float EPSILON = 0.0000001;

	float tmp = i/j;

	if (i/j == k)
	{
		printf("compare immediately: i/j==k\n");
	}
	else if (i/j < k)
	{
		printf("compare immediately: i/j<k\n");
	}
	else
	{
		printf("compare immediately: i/j>k\n");
	}

	if (i/j-k > EPSILON)
	{
		printf("compare d-value with EPSILON: i/j larger\n");
	}
	else if (i/j-k < -EPSILON)
	{
		printf("compare d-value with EPSILON: i/j smaller\n");
	}
	else
	{
		printf("compare d-value with EPSILON: i/j == k \n");
	}

	if (tmp-k > EPSILON)
	{
		printf("tmp larger\n");
	}
	else if (tmp-k < -EPSILON)
	{
		printf("tmp smaller\n");
	}
	else
	{
		printf("tmp == k \n");
	}

	printf("end\n");

	return ;
}

1. if EPSILON==0.000000000000000001, output:

compare immediately: i/j>k
compare d-value with EPSILON: i/j larger
tmp == k

2. if EPSILON==0.0000001, output:

compare immediately: i/j>k
compare d-value with EPSILON: i/j == k
tmp == k