How to get handle of ccombobox in mfc

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Hi,

I am not able to get handle of CComboBox.

C++

CComboBox *pComboBox = reinterpret_cast<ccombobox>(GetDlgItem(IDC_COMBO1));

I checked value of pComboBox is null.

I am surprised, The same line of code is working fine in my other small application but here it fails.

Please provide your input? I need to get handle to combo Box and use the handle.

Regards,
Joy

What I have tried:

C++

CComboBox *pComboBox = reinterpret_cast<ccombobox>(GetDlgItem(IDC_COMBO1));

Posted 15-Feb-16 5:03am

joyjhonson

Updated 15-Feb-16 5:57am

Maciej Los

v2

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nv3 15-Feb-16 11:24am

Check the ID of your combo box. Is it really IDC_COMBO1. Other possible issues:

- code is not executed from within a member function of the window that contains the combo box

- you are executing the code at a stage where the controls of the dialog have not been created yet

Richard MacCutchan 15-Feb-16 11:29am

Your cast statement does not make sense, and should not even compile.

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Aescleal · Answer 1 · 2016-02-15T06:39:00

The line of code you've presented isn't getting the handle to anything - it's apparently trying to recover the pointer to a CComboBox MFC wrapper object that's a child of the window that supplies the this pointer the code is executed under.

So...

IF you really want a pointer to the MFC wrapper object NEVER use reinterpret_cast, use static cast.

C++

auto pComboBox = static_cast<ccombobox>( GetDlgItem( IDC_COMBO1 ) );</ccombobox>

IF you actually want the handle use the m_hWnd member of whatever is returned by GetDlgItem, e.g.

C++

auto handle = GetDlgItem( IDC_COMBO1 )->m_Hwnd;

Try those lines of code and see what happens. If neither do what you want perhaps modify your question to reflect what you want to do!