Develop Reference

Visual studio does not show UI while running app

I have been working on c# for about 3 hours and Visual Studio does not show the UI while running the application. It shows the UI in designer but after compiling and running, it just goes blank.

Two things to test:
In the code file Program.cs, you will find something like this:
static void Main()
{
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
Application.Run(new Form1());
}
Does the name of the form in the line Application.Run match the name of your form?
Your form's code behind (Form1.cs) should have a constructor looking like this
public Form1() // Where the name of the constructor must match the one of the form class.
{
InitializeComponent();
// Your code goes here (if any) ...
}
Does it have this constructor? If yes, does it call InitializeComponent?
InitializeComponent is very important, because it creates the controls and configures the form. You may have replaced it with your own code. Always call it before your initialization code.

I guess the entry point if your application is wrong. Check the solution properties (right click on your application/solution in the solution explorer -> properties ) for the correct entry point.

It looks like you have more than one form.
Go to the Program.cs file and verify if the class of the form is in Application.Run() method
static class Program
{
/// <summary>
/// The main entry point for the application.
/// </summary>
[STAThread]
static void Main ()
{
Application.EnableVisualStyles ();
Application.SetCompatibleTextRenderingDefault (false);
Application.Run (new urltetx());
}
}

Windows form inside console application or vice versa [duplicate]

This question already has an answer here:
How to be dynamically either console application or Windows Application
(1 answer)
Closed 4 years ago.
I have this task given to me and have no idea how to approach it.. Everywhere online says that this isn't possible without .dll or mocking.
The server, when launched with an argument of –w should open a windowed interface that
permits an operator to control the functions of the server. If launched with no arguments it
should operate as previously specified in part 1
(part 1 is a console application)
I don't know if I'm missing something obvious.
Thanks for any help you can give

I don't know where you're seeing on-line that this isn't possible. Every Windows Forms application has a Main method, you just need to modify it a bit.
[STAThread]
static void Main(string[] args)
{
if (args.Length > 0)
{
File.WriteAllText("hello.txt", "foo");
}
else
{
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
Application.Run(new Form1());
}
}
I added the string[] args argument and then check it. I'm not checking for -w, I'm just checking for any old argument, but you should be able to take it from there.

It's absolutely not impossible. Just add reference to System.Windows.Forms, add it in the using clause, and go from here.
using System;
using System.Collections.Generic;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Linq;
namespace ConsoleWindow
{
class Program
{
static void Main(string[] args)
{
if (args.Contains("-w"))
{
Form1 f1 = new Form1();
f1.ShowDialog();
}
Console.ReadKey();
}
}
}

C# custom events doesn't want to work with forms, partial class

I'm creating an app, there is some class that does some background operations and after all is done, parent object is notified using event. To provide event functionality i use following code:
public delegate void ShopStateChangedEventHandler(object sender, QuantityManagerEventArgs ea);
public event ShopStateChangedEventHandler ShopStateChanged;
protected virtual void WhenShopStateChanged(QuantityManagerEventArgs ea)
{
if (ShopStateChanged != null)
{
ShopStateChanged(this, ea);
}
}
It was working fine in all cases while I was using this piece of code with classes I've made, today I needed to have some custom made event added to one of forms in my application. Unfortunately i'm getting build error saying that compiler was unable to find ShopStateChangedEventHandler in form that is parent to form with custom event, and error is about line that adds listener
qmgr.ShopStateChanged += new ShopStateChangedEventHandler(qmgr_ShopStateChanged);
I really have no clue where to look for source of this error while in all other classes where i use this code all works fine, i suspect is it either because fact that the class i try to add custom event inherits from Form or maybe because it is partial class. As for now im far in the woods if it comes to solving it and I have no idea how to crunch it.
I hope you could suggest me what to do, or how to alter my code to make it all work with form.
thanks in advance
mth
EDIT
error is CS2046
The type or namespace name 'type/namespace' could not be found (are you missing a using directive or an assembly reference?)
all classes and forms belong to the same namespace
and as for qmgr_ShopStateChanged for now its just empty method
void qmgr_ShopStateChanged(object sender, QuantityManagerEventArgs ea)
{
}
qmgr is instance of form that contains custom event code, qmgr and qmgr_ShopStateChanged along with code that creates listener and makes problem, belongs to main form of application (frmMain).

Declare your delegate directly on your namespace outside any class.

Can I make a Form a singleton?

I have a Visual C# 2010 application, and it has one main form called MainWnd with other tool windows and dialogs. I want the other tool windows to be able to 'talk' to the main form, and call its methods. But that requires an instance of MainWnd, and since there will only be one of these forms created at any given time there is no reason while I should enumerate through all instances of MainWnd or look for the first one. So I want my main application form MainWnd to be a singleton so other windows can easily call code from it.
Here is the code of the main form that I would like to make a singleton:
using System;
using System.ComponentModel;
using System.Windows.Forms;
namespace MyLittleApp
{
public partial class MainWnd : Form
{
public MainWnd()
{
InitializeComponent();
}
public void SayHello()
{
MessageBox.Show("Hello World!");
// In reality, code that manipulates controls on the form
// would go here. So this method cannot simply be made static.
}
}
}
I am looking to be able to call SayHello() from another form, simply by writing:
MainWnd.SayHello();
How could I accomplish this?

You could probably find a way to make the main window a singleton, however that's not the best way to achieve the outcome you want, nor is it really an appropriate situation in which to use the singleton pattern.
If all of the other tool windows/ dialogs are encapsulated within the main window, then a much better pattern to use for communication would be events.
Have the inner windows/dialogs raise events to represent a 'request' for the main window to do something. Have the main window subscribe to these events, and do the work via the event handlers.
By avoiding the singleton approach, you avoid the difficulties of testing the singleton, as well as avoiding extensive explicit circular references, where not only does the main window have references to the encapsulated windows/dialogs, but they in turn have explicit references back to the main window.

See below.
using System;
using System.ComponentModel;
using System.Windows.Forms;
namespace MyLittleApp
{
public partial class MainWnd : Form
{
public static MainWnd Instance;
public MainWnd()
{
Instance = this;
InitializeComponent();
}
public void SayHello()
{
MessageBox.Show("Hello World!");
// In reality, code that manipulates controls on the form
// would go here. So this method cannot simply be made static.
}
}
}
You can now use it anywhere in your code by calling MainWnd.Instance
All its members are also available to the instance.

You can certainly do this.
public MainWnd Instance = new MainWnd();
Then access as MainWnd.Instance.SayHello().
Replace following calls
MainWind instance = new MainWnd();
To
MainWnd instance = MainWnd.Instance;
I am not sure how Visual Studio designer would react after making the constructor as private though.
But if it does not allow, it will be Visual Studio issue, rather than language/compiler issue.

What is the entering method of a multi form project?

I'm working with a C# project using System.Windows.Form to create the GUI, I have two forms within the VS project( MainForm and InitialPrompt). I've never used Forms before and Google hasn't been of much help.
Intended action:
InitialPrompt Load
Click Button on InitialPrompt
Load MainForm
However, since MainForm was created first there is some property/method that allows it to load first and the InitialPrompt does not load at all. How to I make MainForm the secondary form and InitialPrompt the primary?
Thanks in advance.

namespace WindowsFormsApplication1
{
static class Program
{
/// <summary>
/// The main entry point for the application.
/// </summary>
[STAThread]
static void Main()
{
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
Application.Run(new Form1());
}
}
}
You can change the above code to read
Application.Run(new Form2()); // or whatever the name of the second form is.
This is found in your Program.cs file.

Look for the Program.cs file inside your project. Inside you will see something like this:
[STAThread]
static void Main()
{
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
Application.Run(new MainForm());
}
Just change new MainForm() to new InitialPrompt(). This will make InitialPrompt the main form.

Like any other .Net project it is the static void Main() method in a class defined in your project. Because of this, only one static void Main() method is allowed in a project.
NOTE: this static Main method must be defined as void return type, and it can either take no arguments, or it can be defined to take an array of strings to be passed as command line arguments.