// C# Extension Method

// Doc: https://csharp-extension.com/en/method/1002097/string-removeletter

​

// @nuget: Z.ExtensionMethods

​

using System;

using System.IO;

​

public class Program

{   

    public static void Main()

    {   

        string input = "192.168.1.1a";

​

        //C# Extension Method: String - RemoveLetter

        string output = input.RemoveLetter();

​

        System.Console.WriteLine(output);

​

    }

}