<VB.net> Memo: AllocConsole() (.NET Core)

Environment

• VB.net
• .NET Core 3.1
• Windows 10

Aim

Call a console window from forms, using AllocConsole() function. Especially, the case of calling a console application (project) from a form application (project) in a same solution of Visual Studio.

References

• C#(Windows Formアプリケーション)でコンソールの表示、非表示、出力方法(Console.WriteLine()) - Qiita

Code

Private Declare Function AllocConsole Lib "kernel32" () As Integer
Private Declare Function FreeConsole Lib "kernel32" () As Integer

Sub SomeName()
    AllocConsole()
    Console.SetOut(New StreamWriter(Console.OpenStandardOutput()) With {.AutoFlush = True})

    'Set the size of the console window into an appropriate size.
    Console.SetWindowSize(40, 20)
    Console.SetBufferSize(80, 80)


    Try
        '(...)
    Finally
        FreeConsole()
    End Try


End Sub

Note

• AllocConsole() function allocates a console window to the process.

• Console.SetOut(...) defines the output stream of the console window. Without it, when the procedure Sub SomeName is called twice or more, functions like Console.Writeline(...) would throw exceptions even though after AllocConsole().

  • In some cases, specifying encoding may be needed, like
    Dim enc As Text.Encoding = ...
Console.SetOut(New StreamWriter(Console.OpenStandardOutput(), enc) With {.AutoFlush = True})

• FreeConsole() closes the console window.