共用方式為


use this if it's non-null, otherwise use this default - the ?? feature

This isn't really "new", just a reminder of a neat feature, especially for those of us used to doing something very similar. It works great on Nullable<T> too!

using System;

class Program

{

    static void Main(string[] args)

   {

        int? realInt = 27;

        int? nullInt = null;

        string realString = "foo";

        string nullString = null;

        int defaultInt = -1;

        string defaultString = "default";

        Console.WriteLine("realInt: {0}", realInt ?? defaultInt);

        Console.WriteLine("nullInt: {0}", nullInt ?? defaultInt);

        Console.WriteLine("realString: {0}", realString ?? defaultString);

        Console.WriteLine("nullString: {0}", nullString ?? defaultString);

        // Output:

        // realInt: 27

        // nullInt: -1

        // realString: foo

        // nullString: default

    }

}