[RESOLVED] Find the Alpha Characters on Left Side of String

[Vladamir]

I need to come up with a method to get the alphabetical characters from a string. The strings will always have alpha characters on the left side but it will not always be the same number of them.

Strings will look like this: "A0001", "AA001", "AB021", "ABC12", etc...

I want to get the Alpha part of the string broken out to be used in a variable. I guess I could loop through it until I find the first numeric character, but I was hoping there would be a more efficient method, maybe Regex or something.

[Vladamir]

Okay, I think I got it:

static string GetAlphabeticalValue(string x)
        {
            return (new Regex("[A-Z]*").Match(x).Value);
        }

This appears to work. The string will always contain upper case letters.

[Vladamir]

Okay, I've got this on the way now. The next step is to determine where in the alphabet the last alpha character in the string occurs.

public static string vAlphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";

public static string Right(this string value, int length)
        {
            return value.Substring(value.Length - length);
        }

string vAlphaIndex = vAlpha.Right(1);

I need to find where in the string vAlphabet the character vAlphaIndex occurs at. For example if the last letter in the alpha portion of it is A, then I would need 1, B would be 2, etc.... I guess something similar to INSTR in VB.NET.

[jmcilhinney]

As I'm not really very good with regular expressions, here's how I would have done the first part:

Dim alpha = New String(myString.TakeWhile(Function(ch) Char.IsLetter(ch)).ToArray()

For the second part:

Dim ch = alpha.Last()
Dim number = Convert.ToInt32(Char.ToUpper(ch)) - Convert.ToInt32("A"c) + 1

[jmcilhinney]

Oops! Forgot I was in C# land:

var alpha = new string(myString.TakeWhile(ch => char.IsLetter(ch)).ToArray();
var ch = alpha.Last();
var number = Convert.ToInt32(char.ToUpper(ch)) - Convert.ToInt32('A') + 1;