Quickest way to convert a base 10 number to any base in .NET?

Question

I have and old(ish) C# method I wrote that takes a number and converts it to any base:

string ConvertToBase(int number, char[] baseChars);

Answer 1

This is a fairly straightforward way to do this, but it may not be the fastest. It is quite powerful because it is composable.

public static IEnumerable ToBase(this int x, int b)
{
    IEnumerable ToBaseReverse()
    {
        if (x == 0)
        {
            yield return 0;
            yield break;
        }
        int z = x;
        while (z > 0)
        {
            yield return z % b;
            z = z / b;
        }
    }

    return ToBaseReverse().Reverse();
}

Combine this with this simple extension method and any getting any base is now possible:

public static string ToBase(this int number, string digits) =>
    String.Concat(number.ToBase(digits.Length).Select(x => digits[x]));

It can be used like this:

var result = 23.ToBase("01");
var result2 = 23.ToBase("012X");

Console.WriteLine(result);
Console.WriteLine(result2);

The output is:

10111
11X