26.1. First look at structs

You will be surprised how much structs appear to be like classes at first sight.

A struct is declared in the code below to represent a person's name. This is done using the struct keyword.

 1: using System;
 2:
 3: struct Name {
 4:   private string FirstName;
 5:   private string LastName;
 6:
 7:   public string GetName(){
 8:     return FirstName + " " + LastName;
 9:   }
10:
11:   // accessors and mutators
12:   public string GetFirstName(){
13:     return FirstName;
14:   }
15:   public void SetFirstName(string newFirstName){
16:     FirstName = newFirstName;
17:   }
18:   public string GetLastName(){
19:     return LastName;
20:   }
21:   public void SetLastName(string newLastName){
22:     LastName = newLastName;
23:   }
24: }

That's the Name struct. Now you can instantiate and use it.

25: class TestClass{
26:   public static void Main(){
27:     Name n = new Name();
28:     n.SetFirstName("Charlie");
29:     n.SetLastName("Brown");
30:     Console.WriteLine(n.GetName());
31:   }
32: }

Output:

c:expt>test
Charlie Brown

On line 27, a new instance of the Name struct is created. On lines 28 – 30 its methods are invoked. ^[3]

^[3] In this example, public accessor and mutator methods are used to access the private fields. Structs can also contain public properties instead.

Like classes:

• structs can contain both function members ^[4] and data members ^[5] – they can be static or non-static;

  ^[4] Function members are indexers, constructors, operators, properties, and any method. There is one exception here – a struct cannot have a destructor.

  ^[5] Data members are read-only variables, constants, events, and fields.

• structs can be declared with the following accessibility modifiers – public, protected, internal, and private with the same effect as classes;

• structs can be hidden using the new modifier;

• structs can implement one or more interfaces (though they cannot extend another class or another struct) – to make the Name struct implement the MyInterface interface, just declare the struct like this:

  struct Name:MyInterface{
      ...
  }