C# join list of strings with delimeter

joinlistofstringswithdelimeter.cs

/*
Input : [“hello”, “world”, “message”]
Separator:  “ +++ ” 
 Result: “hello +++ world +++ message”
*/
using System;
using System.Collections.Generic;


var input = new List<string>{"hello","world","message"};
var sep = "+++";

var res = string.Empty;
input.ForEach(x=>res = res+ x+ sep);

Console.WriteLine(res);