How dangerous is it to compare floating point values?

Question

I know `UIKit` uses `CGFloat` because of the resolution independent coordinate system.But every time I want to check if for example `frame.origin.x` is `0` it makes me feel sick: if (theView.frame.origin.x == 0) { // do important operation }Isn't `CGFloat` vulnerable to false positives when comparing with `==`, `<=`, `>=`, `<`, `>`?It is a floating point and they have unprecision problems: `0.0000000000041` for example.Is `Objective-C` handling this internally when comparing or can it happen that a `origin.x` which reads as zero does not compare to `0` as true?

Answer 1

The best thing to do is it find the MACHINE EPSILON, that is

the smallest number you can find such that

1 + MACH_EPS is NOT equal to 1

So there is a floating point MACH_EPS=0.00000.....000001 such that 1+ x = 1;

that is, adding it to ONE has no effect.

Once you find the MACHINE EPSILON for that particular system and platform, you can better troubleshoot

from there