Question

I need to change testAppGUI’s (testAppGUI is a form) visible property from another function. The function is in a separate file and it’s not in a class.

If I try to do

testAppGUI::Visible = false;

I just get error

C2597: illegal reference to non-static member ‘System::Windows::Forms::Control::Visible’

And if I try create a instance of the object like this

testAppGUI^ formProperty = gcnew testAppGUI;

and then do

formProperty->Visible = false; nothing happens?!

Can anybody explain how to do this?

Thanks in advance.

EDIT: Here is some more code

In testApp.cpp

#include "stdafx.h"
#include "testAppGUI.h"

using namespace testApp;

[STAThreadAttribute]
int main(array<System::String ^> ^args)
{
    Application::EnableVisualStyles();
    Application::SetCompatibleTextRenderingDefault(false); 
    Application::Run(gcnew testAppGUI());
    return 0;
}

In testAppGUI.h

#pragma once

#include "HideAndShowGUI.h"

namespace testApp {

    using namespace System;
    using namespace System::ComponentModel;
    using namespace System::Collections;
    using namespace System::Windows::Forms;
    using namespace System::Data;
    using namespace System::Drawing;
    using namespace System::IO;

    public ref class testAppGUI : public System::Windows::Forms::Form
    {

    public:
        testAppGUI(void)
        {
            InitializeComponent();
        }

    protected:
        ~testAppGUI()
        {
            if (components)
            {
                delete components;
            }
        }
    private: System::Windows::Forms::Button^  button1;
    ...

#pragma region Windows Form Designer generated code
        void InitializeComponent(void)
        {
            ...

        }
#pragma endregion

private: System::Void button1_Click(System::Object^  sender, System::EventArgs^  e) {
             hideGUI();
         }
};
}

HideAndShowGUI.cpp

#include "stdafx.h"

#include "testAppGUI.h"

using namespace testApp;

void hideGUI(){
    //Hide the form, this function should be able to be called by all functions in the program. Not just from forms!

}

void showGUI(){
    //Unhide/Show the form, this function should be able to be called by all functions in the program. Not just from forms!

}

hideGUI and showGUI is declared in HideAndShowGUI.h

Answer 1

If you already have an instance of the form which you want to hide, you will have to pass a reference to that form to the function where you want to change the property.

You can do this either by directly supplying the form as a parameter of the function or if the function is a member of a class, you can pass the form to (and instance of) the class (and store it as a member variable). Which of these is more appropriate for you depends on your specific context, which we do not have access to without some more of your code.

Note: Your first snipet is conflicting with your second: in the first you are using form1 as a variable, in the second as a type. If you already have the variable form1, you can just set its property:

form1->Visible = false;