using System;

public class Program

{

​

    public static void Main()

    {

        char[] inNumberArray = new char[]{'1','2','0','5'};

        var asString = string.Join("", inNumberArray);

        var asInt = int.TryParse(asString, out int outNum)?outNum:0;

        Console.WriteLine($"asString: {asString}");

        Console.WriteLine($"asInt: {asInt}");

    }

}