Question about if statement

[127.0.0.1]

I understand that C having no boolean values uses Ints and Null checks in if statements. However, I came across some code and would like to know why the programmer chose to use null check if statements. Is it only error checking or is it something to avoid function overloading?

void AngleVectors (vec3_t angles, vec3_t forward, vec3_t right, vec3_t up)
{
	float		angle;
	static float		sr, sp, sy, cr, cp, cy;
	// static to help MS compiler fp bugs

	angle = angles[YAW] * (M_PI*2 / 360);
	sy = sin(angle);
	cy = cos(angle);
	angle = angles[PITCH] * (M_PI*2 / 360);
	sp = sin(angle);
	cp = cos(angle);
	angle = angles[ROLL] * (M_PI*2 / 360);
	sr = sin(angle);
	cr = cos(angle);

	if (forward)
	{
		forward[0] = cp*cy;
		forward[1] = cp*sy;
		forward[2] = -sp;
	}
	if (right)
	{
		right[0] = (-1*sr*sp*cy+-1*cr*-sy);
		right[1] = (-1*sr*sp*sy+-1*cr*cy);
		right[2] = -1*sr*cp;
	}
	if (up)
	{
		up[0] = (cr*sp*cy+-sr*-sy);
		up[1] = (cr*sp*sy+-sr*cy);
		up[2] = cr*cp;
	}
}

[Salem]

> // static to help MS compiler fp bugs
What kind of lame comment/excuse is this?
At the very least, it should cite specific compiler versions and bug report numbers.

The NULL checks allow users to do things like this:
AngleVectors( angles, result, NULL, NULL );

It's a fairly common technique for providing a generalised function, with the option to omit returning results which you're not interested in at the moment.

[127.0.0.1]

> // static to help MS compiler fp bugs
What kind of lame comment/excuse is this?
At the very least, it should cite specific compiler versions and bug report numbers.

Lol yea, this code is actually part of the quake 2 engine its filled with comments like that.

Anyway, I had a feeling it was a way to get around function overloading. Thanks for the clarification.