Книга: C# 2008 Programmer

Implementing an Interface

Implementing an Interface

Once an interface is defined, you can create a new class to implement it. The class that implements that particular interface must provide all the implementation for the members defined in that interface.

For example, here's an Employee class that implements the IPerson interface:

public class Employee : IPerson {
 public string Name { get; set; }
 public DateTime DateofBirth { get; set; }
 public ushort Age() {
  return (ushort)(DateTime.Now.Year - this.DateofBirth.Year);
 }
}

To implement an interface, you define your class and add a colon (:) followed by the interface name:

public class Employee : IPerson

You then provide the implementation for the various members:

{
 public string Name { get; set; }
 public DateTime DateofBirth { get; set; }
 public ushort Age() {
  return (ushort)(DateTime.Now.Year - this.DateofBirth.Year);
 }

Notice that I'm using the new automatic properties feature (discussed in Chapter 4) in C# 3.0 to implement the Name and DateofBirthproperties. That's why the implementation looks the same as the declaration in the interface.

As explained, all implemented members must have the public access modifiers.

You can now use the class as you would a normal class:

Employee e1 = new Employee();
e1.DateofBirth = new DateTime(1980, 7, 28);
el.Name = "Janet";
Console.WriteLine(e1.Age()); //---prints out 28--- 

This could be rewritten using the new object initializer feature (also discussed in Chapter 4) in C# 3.0:

Employee el = new Employee() {
 DateofBirth = new DateTime(1980, 7, 28),
 Name = "Janet"
};
Console.WriteLine(e1.Age()); //---prints out 28---

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