ASP.Net Example

using System;
using System.Runtime.InteropServices;

class DllImportDemo
{
[DllImport("User32.dll", EntryPoint="MessageBox")]
static extern int MessageDialog(int inthWnd,string strmsg,string strCaption,int intMsgType);

    [STAThread]
    static void Main(string[] args)
    {
        MessageDialog(0, "MessageDialog is Called!", "DllImport Demo", 1);
    }
}