Question

I want to add a method to string that convert space char to underscore (extension method), I deployed the code but why it doesn’t work?

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            string name = "moslem";
            string.SpaceToUnderScore(name);
        }

        public static string SpaceToUnderScore(this string source)
        {
            string result = null;
            char[] cArray = source.ToArray();
            foreach (char c in cArray)
            {
                if (char.IsWhiteSpace(c))
                {
                    result += "_";
                }
                else
                {
                    result += c;
                }
            }
            return result;
        }
    }
}

Why doesn’t it work?

Answer 1

First put your extension method to a static class then invoke as name.SpaceToUnderScore()

var newstr = "a string".SpaceToUnderScore();


public static class SomeExtensions
{
    public static string SpaceToUnderScore(this string source)
    {
        return new string(source.Select(c => char.IsWhiteSpace(c) ? '_' : c).ToArray());
        //or
        //return String.Join("",source.Select(c => char.IsWhiteSpace(c) ? '_' : c));
    }
}