如果我不知道变量是正/负，如何在不调用函数或不使用if的情况下使其变为正数？

Question

This is the code (Java):

    float yd = waypointY - currentY;
    if (yd < 0) {
        yd = yd*(-1);
    }

I don't think this is the best way to do it, and have searched but only found results for when you already know if it's positive or negative. I never know if waypointY is more or less than currentY.

Answer 1

if you use java , there is an API you can use, Math.abs(xy) it will return the absolute value of xy and the source code of abs API as below:

public static float abs(float a) {
    return (a <= 0.0F) ? 0.0F - a : a;
}

Answer 2

AFAIK, this is impossible without if. Or some variation of. Maybe get the sign bit and multiply by something and add something and do something? This seems way too complex, any particular reason not to use if?

Edit: you could use a ternary (or whatever it's called) expression:

x = y < 0 ? -y : y;