Работа c StringBuilder - C#

using System;
using System.Text;
 
class Program
{
    private enum CharType { SPACE, PUNCT, OTHER };
 
    public static void Main()
    {
        string str = "Совхоз «Светлый путь».";
        StringBuilder sb = new StringBuilder(str.Length);
        int spaces = 0;
        foreach (char ch in str)
        {
            CharType charType = Char.IsWhiteSpace(ch) ? CharType.SPACE : Char.IsPunctuation(ch) ? CharType.PUNCT : CharType.OTHER;
            if (charType == CharType.SPACE) ++spaces;
            if (charType != CharType.PUNCT) sb.Append(Char.ToLower(ch));
        }
        Console.WriteLine(sb.ToString());
        Console.WriteLine(spaces);
    }
}