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.