#782 – You Can Create an Instance of a struct Without the new Keyword

Like a class, you can create an instance of a struct using the new keyword.  You can either invoke the default parameterless constructor, which initializes all fields in the struct to their default values, or you can invoke a custom constructor.

            // Method 1 - Parameterless constructor, data in struct initialized to default values
            DogCollar collar = new DogCollar();

            // Method 2 - Call custom constructor
            DogCollar collar2 = new DogCollar(10.0, 0.5);

In either case, a constructor is called.

You can also create an instance of a struct by just declaring it, without using the new operator.  The object is created, although you can’t use it until you’ve explicitly initialized all of its data members.

            // Method 3 - Just declare it
            DogCollar collar3;

            // Error - Can't use collar3 yet (use of unassigned field)
            Console.WriteLine(collar3.Length);

We need to first initialize all data members:

            // Correct - initialize first
            DogCollar collar3;
            collar3.Length = 10.0;
            collar3.Width = 5.0;
            Console.WriteLine(collar3.Length);