C# Open a form from another form, which is located in a different project

Question

I have two different projects, DriverSide and LogInForm . In both of them is a form, in DriverSide the form Form1 will be executed on the start of the application and in LogInForm the important form is the UserOnTrip form. On Form1 is a button and with it´s click event i want to open the UserOnTrip form, but i dont know how to handle it because the forms are on different projects.

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This is my button click method:

private void _btnAccept_Click(object sender, EventArgs e)
{
        LogInForm._pnlUserOntrip _pnl = new LogInForm._pnlUserOntrip();
        _pnl.Show();
        //System.Diagnostics.Process.Start(Application.StartupPath.ToString() + @"\_pnlUserOnTrip.exe");

        LogInForm.LoadingScreen _load = new LogInForm.LoadingScreen();
        _load.Hide();
    }
}

And this is the layout of my solution explorer:

Answer 1

Go to your solution explorer and right click on the project you want to execute. Now click 'Set as start project'. This project gets highlighted then a bit, you should see atleast any difference.

Have a look at this picture . There are the two different projects: John.Socialclub.Data and John.Socialclub.Desktop. And you dont click on any of those files below, right click on of your projects itself and set them simply as start project.

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Updated:

So i understood it that way, that you execute in the project DriverSide the Form1 . On this form you have a button which shell open the form UserOnTrip which is located in the LogInForm project.

First of all you want to add a reference to the DriverSide project. Go once again to the solution explorer and righ click on References . Then click Add reference . Then a menu pops up where you select on the left side projects . Now there should be your project LogInForm listed, you select it with the comboBox and press OK.

Now we are in the Form1 of DriverSide :

In the beginning note that you have to add this using reference to use the reference to the LogInForm . Add this to the other using references.

using LogInForm;

namespace DriverSide
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void _btnAccept_Click(object sender, EventArgs e)
        {
            UserOnTrip testWindow = new UserOnTrip();
            testWindow.Show();
        }
    }
}

I just copied your button click method _btnAccept_Click . Insert this code and you should be fine. You can ignore the constructor public Form1() , i just placed it in there that you feel familiar with your code and understand exactly where to place what.