using System;

using System.Collections.Generic;

​

public static class EnumerableExtension

{

    public static int FirstIndexMatch<TItem>(this IEnumerable<TItem> items, Func<TItem, bool> matchCondition)

    {

        var index = 0;

        foreach (var item in items)

        {

            if (matchCondition.Invoke(item))

            {

                return index;

            }

​

            index++;

        }

​

        return -1;

    }

}

​

public class Program

{

    public static void Main()

    {

        var test = new[]

        {

        '\0', '\0', '\0', '\0', '1', '2', '3', '\0', '5'

        }

​

        ;

        var s = new string (test);

        Console.WriteLine("{0} -> length: {1}", s, s.Length);

        Console.WriteLine("First non-NUL at: {0}", test.FirstIndexMatch(ch => ch != '\0'));

    }

}