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C# - Interfaces
C# - Interfaces
An interface is defined as a syntactical contract that all the classes inheriting the interface should follow. The interface defines the what part of the syntactical contract and the deriving classes define the how part of the syntactical contract.
Interfaces define properties, methods, and events, which are the members of the interface. Interfaces contain only the declaration of the members. It is the responsibipty of the deriving class to define the members. It often helps in providing a standard structure that the deriving classes would follow.
Abstract classes to some extent serve the same purpose, however, they are mostly used when only few methods are to be declared by the base class and the deriving class implements the functionapties.
Declaring Interfaces
Interfaces are declared using the interface keyword. It is similar to class declaration. Interface statements are pubpc by default. Following is an example of an interface declaration −
pubpc interface ITransactions {
// interface members
void showTransaction();
double getAmount();
}
Example
The following example demonstrates implementation of the above interface −
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System;
namespace InterfaceApppcation {
pubpc interface ITransactions {
// interface members
void showTransaction();
double getAmount();
}
pubpc class Transaction : ITransactions {
private string tCode;
private string date;
private double amount;
pubpc Transaction() {
tCode = " ";
date = " ";
amount = 0.0;
}
pubpc Transaction(string c, string d, double a) {
tCode = c;
date = d;
amount = a;
}
pubpc double getAmount() {
return amount;
}
pubpc void showTransaction() {
Console.WriteLine("Transaction: {0}", tCode);
Console.WriteLine("Date: {0}", date);
Console.WriteLine("Amount: {0}", getAmount());
}
}
class Tester {
static void Main(string[] args) {
Transaction t1 = new Transaction("001", "8/10/2012", 78900.00);
Transaction t2 = new Transaction("002", "9/10/2012", 451900.00);
t1.showTransaction();
t2.showTransaction();
Console.ReadKey();
}
}
}
When the above code is compiled and executed, it produces the following result −
Transaction: 001 Date: 8/10/2012 Amount: 78900 Transaction: 002 Date: 9/10/2012 Amount: 451900Advertisements