Console.Write Not Working In Win Forms App

Question

I created a VB.NET Windows Forms Application in Visual Studio 2008. When I run my program from the command-line, I get no output (only the next prompt).

What am I doing wrong?

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
    Debug.Write("Foo")
    Debug.Flush()
    Console.WriteLine("foo")
    Console.Beep(800, 100) 'confirm this function is called'
    Me.Close()
End Sub

EDIT: Can a program have a form and a console?

EDIT2: Ho's answer works. However, the output appears on the next command-line prompt. Can a Winforms application tell the command-line to wait until it's finished instead of immediately returning?

Answer 1

Tested similar code with a C# .NET Windows Form Application. Outputs and beeps nicely within Visual Studio but only beeps when run at the command line.

If I change the Output Type to Console Application under the Application tab for the Project properties, I get to use both the form and console :)

Answer 2

You can run your app from the console using myApp.exe|MORE
This way the console will show Console.WriteLine() calls coming from the app and will wait until the app exits.
Please excuse my bad english.

Answer 3

The others are correct in saying that you need to run your app as a console app. To your question of whether you can have both a console and a GUI: yes. Simply add a reference to System.Windows.Forms to your project, and for the app's Main method, include this code:

' here instantiate whatever form you want to be your main form '
Dim f As New Form1

' this will start the GUI loop, which will not progress past '
' this point until your form is closed '
System.Windows.Forms.Application.Run(f)

Answer 4

Or if you already have a WinForms application you can attach a Console to it using the AttachConsole API.

using System.Runtime.InteropServices;  

...

[DllImport("kernel32.dll")] static extern bool AttachConsole(int dwProcessId);
private const int ATTACH_PARENT_PROCESS = -1;  

...

AttachConsole(ATTACH_PARENT_PROCESS);

(Formatted as code)

Answer 5

尝试使用“控制台应用程序”模板创建一个新项目。

Answer 6

The solution is:

Declare Function AttachConsole Lib "kernel32.dll" (ByVal dwProcessId As Int32) As Boolean
Declare Function FreeConsole Lib "kernel32.dll" () As Boolean

[code.....]

when needed the console output you just call AttachConsole(-1) but remember to do a FreeConsole() at the end of your program.

the only problem with this solution is that you will read something like this:

C:>yourapp.exe
C:>Hello World!

That's because a forms application runs as a child of the command prompt so the prompt returns immediately after you type the app name..

In a console application the command prompt returns after the program exits.

I am still trying to find a way to have the same behaviour (sync run) as in a console application.

Answer 7

您必须创建一个命令行/控制台应用程序而不是Windows窗体应用程序才能使用控制台。