How do I find if two variables are approximately equals?

Question

I am writing unit tests that verify calculations in a database and there is a lot of rounding and truncating and stuff that mean that sometimes figures are slightly off.

Answer 1

You could provide a function that includes a parameter for an acceptable difference between two values. For example

// close is good for horseshoes, hand grenades, nuclear weapons, and doubles
static bool CloseEnoughForMe(double value1, double value2, double acceptableDifference)
{
    return Math.Abs(value1 - value2) <= acceptableDifference; 
}

And then call it

double value1 = 24.5;
double value2 = 24.4999;

bool equalValues = CloseEnoughForMe(value1, value2, 0.001);

If you wanted to be slightly professional about it, you could call the function ApproximatelyEquals or something along those lines.

static bool ApproximatelyEquals(this double value1, double value2, double acceptableDifference)