How do I find the Excel column name that corresponds to a given integer? [duplicate]

Answer 1

I currently use this, but I have a feeling that it can be optimized.

private String GetNthExcelColName(int n)
{
    String firstLetter = "";  
    //if number is under 26, it has a single letter name
    // otherwise, it is 'A' for 27-52, 'B' for 53-78, etc
    if(n > 26)
    {
        //the Converts to double and back to int are just so Floor() can be used
        Double value = Convert.ToDouble((n-1) / 26);
        int firstLetterVal = Convert.ToInt32(Math.Floor(value))-1;
        firstLetter = Convert.ToChar(firstLetterValue + 65).ToString();
    }    

    //second letter repeats
    int secondLetterValue = (n-1) % 26;
    String secondLetter = Convert.ToChar(secondLetterValue+65).ToString();

    return firstLetter + secondLetter;
}