浮点数比较大小

#include <iostream>
using namespace std;
//浮点数仅仅是实数在某种范围内的一种近似
const double delta = 0.000001;

bool equal(double x, double y)
{
return (x < y + delta) && (x > y - delta);
}
void main()
{
double x = 1.3;
double y = 0.4;
double z = x + y;
bool result = equal(z, 1.7);
cout << "1.3 + 0.4是否等于1.7?" << endl;
if ( result == true)
{
cout << "YES" << endl;
}
else
{
cout << "NO" << endl;
}

}