Returning the nearest multiple value of a number

Question

I need a function by which I will be able to convert a number to a nearest value of a given multiple.

Eg i want an array of number to be set to the neareast multiple of 16, so 2 = 0, 5 = 0, 11 = 16, 17 = 16, 30 = 32 etc

thanks

Answer 1

In case of rounding of to the nearest multiple of a float, you can use this:

public static float convert(float value, float multipleOf) 
{
    return (float) Math.Round((decimal)value / (decimal)multipleOf, MidpointRounding.AwayFromZero) * multipleOf;
}

Then you can use the function like this:

Console.WriteLine("Convert 10.723: " + convert(10.723f, 0.5f)); // 10.5

Answer 2

Some division and rounding should be all you need for this:

int value = 30;
int factor = 16;
int nearestMultiple = 
        (int)Math.Round(
             (value / (double)factor),
             MidpointRounding.AwayFromZero
         ) * factor;

Be careful using this technique. The Math.Round(double) overload believes the evil mutant MidpointRounding.ToEven is the best default behavior, even though what we all learned before in school is what the CLR calls MidpointRounding.AwayFromZero. For example:

var x = Math.Round(1.5); // x is 2.0, like you'd expect
x = Math.Round(0.5); // x is 0. WAT?!