Syntax Error "=="

Question

this is part of my code to my game engine that I am working on. When I build/debug the code, it stops with a compiler error: "Camera.cpp(70): error C2059: syntax error : '==' " and line 70 is the

if ( near == far ) line. It also happens on line 75:

(if near == NULL || far == NULL)

bool Camera::SetClippingPlanes( float near, float far )
{
    if (near == far)  //Line 70(First Error)
    { 
        MessageBox(NULL, L"ERROR: The far and near clipping planes cannot be equal!", L"Error", MB_OK | MB_ICONERROR);
        return false;
    }
    else
    {
        if (near == NULL || far == NULL)  //Line 75(Second Error)
        {
            MessageBox(NULL, L"ERROR: Near and/or Far clipping planes are null!", L"Error", MB_OK | MB_ICONERROR);
            return false;
        }
        else
        {
            nearPane = near;
            farPane = far;
            return true;
        }
    }
}

I have other functions which use the == operator in the same way, but they do not receive an error. Thanks if you have any suggestions...

Answer 1

Many years ago (in a galaxy far, far away) near and far were keywords. It looks like your compiler still thinks they are - it's probably trying to be helpful.

You either need to pick different names, or figure out how to turn off this particular backward-compatible 'feature'.

Answer 2

You are coding for windows and in windows if you include windows.h or a file that include it( and certainly you include it, because you have a call to MessageBox ) then far and near are both defined in windef.h and you can't use them as variable names

Answer 3

It is also dangerous to compare floats with ==. Its not possible to represent every number with absolute precision. I believe the main ieee floating implementations are only good to 6 significant places. You'll find two ways or calculating what should be the same number will be out by 0.000001 or less and therefore wont be equal.