create class library and call it in basic program in c#

Go on File -- New -- Project -- choose Class library --  Give your library name--ok


using System;

namespace library
{
    public class lib
    {
        static public int sum(int a, int b)
        {
            return (a + b);
        }
    }
}

• Then compile it

Now call it in basic program :

Go on File -- New -- Project -- choose Console Application -- Give your   Console Application _name--ok

For setting

Go on Project -- Add Reference -- Browse -- choose location where Console Application save -- bin-- Debug--  library_name.dll

using System;

namespace class_sum_library

{

    class Program

    {

        static void Main(string[] args)

        {

            int a, b, c;

            Console.WriteLine("Enter number for a:");

            a = int.Parse(Console.ReadLine());

            Console.WriteLine("Enter number for b:");

            b = int.Parse(Console.ReadLine());

            c = a + b;

            library.lib.sum(a, b);

            Console.WriteLine("Sum is:" + c);

            Console.ReadKey();

            

        }

    }

}

output



Enter number for a:
400
Enter number for b:
234
Sum is:634