Why does it cannot work?Could you tell me the mistake?
or tell me other methods that can use DLL.
Thanks very much!!!

Codes are below:

1)This is a dll code:

using System;
namespace myClassLib
{
    public class myCL
    {
        public myCL()
        {
        }

        public double Add(double i,double j)
        {
            return(i+j);
        }
    }
}

2)This is my mainframe:

using System;
using myClassLib;

namespace test1
{
        .......

        myCL cl=new myCL();

        [STAThread]
    static void Main()
    {
        Application.Run(new Form1());
    }

    private void btn_equal_Click(object sender,System.EventArgs e)
    {
        double js=3,bjs=2;
        try
        {
        this.label1.Text=cl.Add(js,bjs).ToString();
        }
        catch
        {
        }
    }
}


Candle

because when you compile your codes to a DLL file you should add its reference in the destination application(or copy the DLL file to the /Bin directory of the destination app).

_____________
Mehdi.
software student.

Thanks,mehdi62b!
I have added the reference in the DLL codes,and the error reads :"cannt find the namespace myClassLib".

Candle

I suppose you are using Visual Studio... You have to add the reference in the Solution Explorer; that is, you have to let the project, which holde the Main method, know which .dll file the namespace myClassLib is in.

Therefore if the two .dll's are in the same solution you have to right-click the References folder in the Solution Explorer and click Add reference. Then select the Projects tab sheet and then select the project which have the .dll file with myClassLib. Finally click OK and then compile.

Hope it helps, Jacob.