How do I tell how far an item is in a string in a list in C#-CodePudding

Example:

    List<string> letters = new List<string>();

        letters.Add("A");
        letters.Add("B");
        letters.Add("C");
        letters.Add("D");
        letters.Add("E");
        letters.Add("F");
        letters.Add("G");
        letters.Add("H");
        letters.Add("I");
        letters.Add("J");
        letters.Add("K");
        letters.Add("L");
        letters.Add("M");
        letters.Add("N");
        letters.Add("O");
        letters.Add("P");
        letters.Add("Q");
        letters.Add("R");
        letters.Add("S");
        letters.Add("T");
        letters.Add("U");
        letters.Add("V");
        letters.Add("W");
        letters.Add("X");
        letters.Add("Y");
        letters.Add("Z");

If I had somebody input a letter in the list, how could I tell which number of the alphabet it is

CodePudding user response：

You can request the zero-based index of a listitem by using List<T>.IndexOf(item).

However, for finding out what letter of the alphabet a character is I suggest converting the char to a byte and substracting the offset: (byte)[charToCheck]-96, e.g. (byte)'a'-96 will return 1

You could write an extension method for this purpose like so:

// startingIndex specifies if the first character of the alphabet should be 0 or any other number
public static Int32 GetPositionInAlphabet(this char character, Int32 startingIndex = 0)
{
    return (byte)Char.ToLower(character) - 97   startingIndex;  
}

CodePudding user response：

It is letters.IndexOf(theletter) 1

IndexOf returns the 0-based index, that is, 0 for the first item, 1 for the second item, etc. This is why the 1 is needed.