using System;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {       

        foreach (var limit in new int[] { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29}){

            Console.WriteLine(Truncate("Hello world this is a text string of epic proportions indeed", limit));

        }

    }

    private const string Ellipsis = "...";

​

    /// <summary>

    /// Truncate a string, preserving the last word.

    /// </summary>

    /// <param name="text"></param>

    /// <param name="charLimit">Max chars to keep from the original text.</param>

    /// <returns>A string of length smaller than or equal to charLimit, or the first 30 chars to last word plus ...</returns>

    public static string Truncate(string text, int charLimit)

    {

        if (string.IsNullOrWhiteSpace(text)) return string.Empty;

        if (text.Length <= charLimit) return text;

        text = text.Substring(0, charLimit);

        var lastIndex = text.LastIndexOf(' ');

        if (lastIndex == -1)

        {

            lastIndex = charLimit - 1;

        }

        else

        {

            lastIndex = Math.Min(text.LastIndexOf(' ') - 1, charLimit - 1);

        }

        text = text.Substring(0, lastIndex + 1);

        return text + Ellipsis;

    }

}