How to keep console window open

Put a Console.Read() as the last line in your program. That will prevent it from closing until you press a key

static void Main(string[] args)
{
    StringAddString s = new StringAddString();
    Console.Read();            
}

If you want to keep it open when you are debugging, but still let it close normally when not debugging, you can do something like this:

if (System.Diagnostics.Debugger.IsAttached) Console.ReadLine();

Like other answers have stated, the call to Console.ReadLine() will keep the window open until enter is pressed, but Console.ReadLine() will only be called if the debugger is attached.

There are two ways I know of

1) Console.ReadLine() at the end of the program. Disadvantage, you have to change your code and have to remember to take it out

2) Run outside of the debugger CONTROL-F5 this opens a console window outside of visual studio and that window won't close when finished. Advantage, you don't have to change your code. Disadvantage, if there is an exception, it won't drop into the debugger (however when you do get exceptions, you can simply just rerun it in the debugger)