Has more than one entry point defined error

Question

I have the following code:

namespace WpfApplication2
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MyWindow : Window
    {
        public MyWindow()
        {
            Width = 300; Height = 200; Title = "My Program Window";
            Content = "This application handles the Startup event.";
        }
    }

    class Program
    {
        static void App_Startup(object sender, StartupEventArgs args)
        {
            MessageBox.Show("The application is starting", "Starting Message");
        }

        [STAThread]
        static void Main()
        {
            MyWindow win = new MyWindow();

            Application app = new Application();
            app.Startup += App_Startup;

            app.Run(win);
        }
    }
}

When I run this code, I get the following error:

Error 1 Program 'c:...\WpfApplication2\WpfApplication2\obj\Debug\WpfApplication2.exe' has more than one entry point defined: 'WpfApplication2.Program.Main()'. Compile with /main to specify the type that contains the entry point.

There isn't any "Program" file in my code as far as I see. How can I fix this?

Take a look in your App.xaml. Is there in the Application-Tag the StartupUri set? — Tomtom, Jul 03 '14 at 07:17
I have this in App.xaml : StartupUri="MainWindow.xaml"> Should I delete that line? — jason, Jul 03 '14 at 07:18
I suggest you could delete `static void Main()` as `App.xaml` is more appropriate for determining WPF startup — pushpraj, Jul 03 '14 at 07:22
@pushpraj then how could I implement Main's functionality? Thanks. — jason, Jul 03 '14 at 07:28
@jason there's probably an event you can subscribe to or a method you can `override`, that will be invoked during initialization. — Marc Gravell, Jul 03 '14 at 07:33

score 5 · Accepted Answer · edited Jun 15 '20 at 09:52

You have two primary options to implement on start activities:

Event handlers

File App.xaml

<Application x:Class="CSharpWPF.App"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             StartupUri="MainWindow.xaml"
             Startup="Application_Startup">

Define Startup="Application_Startup" and handle in file App.xaml.cs:

    private void Application_Startup(object sender, StartupEventArgs e)
    {
        // On start stuff here
    }

Override method

File App.xaml.cs

public partial class App : Application
{
    protected override void OnStartup(StartupEventArgs e)
    {
        // On start stuff here
        base.OnStartup(e);

        // Or here, where you find it more appropriate
    }
}

This might be the intended way to do this, but it's still possible to specify a custom Main method: http://stackoverflow.com/questions/6156550/replacing-the-wpf-entry-point — Roman Starkov, Nov 27 '15 at 17:56

score 0 · Answer 2 · edited Jun 15 '20 at 09:54

0

In order to solve this error, don't change the name of the .cs file when creating new code.

If you want a new name for your .cs file then you have to delete everything in the folder where your project is i.e., the fragments of files (bin, obj folders, etc.).

edited Jun 15 '20 at 09:54

Peter Mortensen

30,738
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answered Oct 04 '19 at 06:26

ALi

1
1

Has more than one entry point defined error

2 Answers2

Event handlers

Override method

Linked

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