User Defined Class Libraries or Dlls

Once a component is designed it can be reused from any kind of application like in console application or windows application or web application or device application etc.

Once a component is designed in any programming language of .net it can be reused from any other programming languages of .Net; i.e., .Net components or assemblies will provide language interoperability.

To create components in .Net, we use class library templates.

End user will never interact with some applications; but will interact with components or DLL.

Program for creating a Component / Assembly

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace CLibMaths
{
public class Arithmatic
{
public int Num1, Num2, Result;
public int PNum1
{
set {
Num1 = value;
}
get {
return Num1;
}
}
public int PNum2 {
set {
Num2 = value;
}
}
public int PResult {
get {
return Result;
}
}
public int Add() {
Result = Num1 + Num2;
return Result;
}
public void Subtract() {
Result = Num1 - Num2;
}
public void Multiply() {
Result = Num1 * Num2;
}
public void Divide() {
Result = Num1 / Num2;
}
}
}

ADD a new class with name ClsMathNumbers

Change the accessibility of the class to public and write following code.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace CLibMaths
{
public class ClsMathNumbers
{
public int Square(int x) {
return x * x;
}
public int Cube(int x) {
return x * Square(x);
}
public int Factorial(int x) {
int R = 1;
for (int i = 1; i <= x; i++) {
R = R * i;
}
return R;
}
}
}

Building the solution will create a DLL. this dll is known as .net component. To see the DLL go to the \bin\Debug folder of the application , you find the CLibMaths.dll.