Fastest function to generate Excel column letters in C#

Question

What is the fastest c# function that takes and int and returns a string containing a letter or letters for use in an Excel function? For example, 1 returns \"A\", 26 return

Answer 1

It is recursive. Fast, and right :

class ToolSheet
{


    //Not the prettyest but surely the fastest :
    static string[] ColName = new string[676];


    public ToolSheet()
    {
        ColName[0] = "A";
        for (int index = 1; index < 676; ++index) Recurse(index, index);

    }

    private int Recurse(int i, int index)
    {
        if (i < 1) return 0;
        ColName[index] = ((char)(65 + i % 26)).ToString() + ColName[index];

        return Recurse(i / 26, index);
    }

    public string GetColName(int i)
    {
        return ColName[i - 1];
    }



}