Floating point division returns integer numbers [duplicate]

Question

I want to calculate the average of two floating point numbers, but whatever the input, I am getting an integer returned.

What should I do to make this work?

public class Program
{
    public static float Average(int a, int b)
    {
        return (a + b) / 2;
    }

    public static void Main(string[] args)
    {
        Console.WriteLine(Average(2, 1));
    }
}

Answer 1

There're two problems with your code

1. Evident one - Integer division - e.g. 1 / 2 == 0 not 0.5 since result must be integer
2. Hidden one - Integer overflow - e.g. a + b can overflow int.MaxValue and you'll get negative result

The most accurate implementation is

public static float Average(int a, int b)
{
    return 0.5f * a + 0.5f * b;
}

Tests:

Average(1, 2);                       // 1.5
Average(int.MaxValue, int.MaxValue); // some large positive value