Heute musste ich bei einem kleinen Projekt den Spaltenindex anhand des oder der Buchstaben ermitteln. Wahrscheinlich gibt es dafür bereits etwas fertiges. Nichts desto trotz habe ich mir selbst etwas einfallen lassen. ;-)

public int GetColumnIndexByLetter(char[] cs)
{
    int index = 0;
    int tempIndex = 0;

    for (int i = cs.Length, j = 0; i > 0; i--, j++)
    {
        switch (cs[j])
        {
            case 'A':
                tempIndex = 1;
                break;
            case 'B':
                tempIndex = 2;
                break;
            case 'C':
                tempIndex = 3;
                break;
            case 'D':
                tempIndex = 4;
                break;
            case 'E':
                tempIndex = 5;
                break;
            case 'F':
                tempIndex = 6;
                break;
            case 'G':
                tempIndex = 7;
                break;
            case 'H':
                tempIndex = 8;
                break;
            case 'I':
                tempIndex = 9;
                break;
            case 'J':
                tempIndex = 10;
                break;
            case 'K':
                tempIndex = 11;
                break;
            case 'L':
                tempIndex = 12;
                break;
            case 'M':
                tempIndex = 13;
                break;
            case 'N':
                tempIndex = 14;
                break;
            case 'O':
                tempIndex = 15;
                break;
            case 'P':
                tempIndex = 16;
                break;
            case 'Q':
                tempIndex = 17;
                break;
            case 'R':
                tempIndex = 18;
                break;
            case 'S':
                tempIndex = 19;
                break;
            case 'T':
                tempIndex = 20;
                break;
            case 'U':
                tempIndex = 21;
                break;
            case 'V':
                tempIndex = 22;
                break;
            case 'W':
                tempIndex = 23;
                break;
            case 'X':
                tempIndex = 24;
                break;
            case 'Y':
                tempIndex = 25;
                break;
            case 'Z':
                tempIndex = 26;
                break;
        }

        if (i == 1)
            index += tempIndex;
        else
            index += tempIndex * ((i-1) * 26);
    }

    return index;
}