CDC exist or not question

[econy]

Hi, in a program, I want to judge if a CDC object is exist, or NULL. don't know how can I do it. Thanks in advance for any suggestions

[econy]

can I use m_hDC == NULL to decide it?

[CPallini]

In a clean scenario, it should be enough.

Veni, vidi, vici.

[econy]

I am kind of not understand what is a clean scenario. did you mean a clean scenario, the m_hDC is NULL?

[CPallini]

For instance, messing MFC with WINAPI is NOT a clean scenario: you could call ::DeleteDC(m_hDC) and then the GDI object would exist no more but m_hDC would be NOT NULL.

Veni, vidi, vici.

[econy]

Tested, set break point, it seems m_hDC, the member variable of CDC, if CDC object was not initialized, it is NULL.

[CPallini]

OK. That's not a proof, of course, however it is reassuring.

Veni, vidi, vici.

[Joe Woodbury]

My preferred method is to call CDC::GetSafeHdc() and test the return value for NULL.