Does C++ support 'finally' blocks? (And what's this 'RAII' I keep hearing about?)

Question

Does C++ support \'finally\' blocks?

What is the RAII idiom?

What is the difference between C++\'s RAII idiom and C#\'s \'using\' statement?

Answer 1

FWIW, Microsoft Visual C++ does support try,finally and it has historically been used in MFC apps as a method of catching serious exceptions that would otherwise result in a crash. For example;

int CMyApp::Run() 
{
    __try
    {
        int i = CWinApp::Run();
        m_Exitok = MAGIC_EXIT_NO;
        return i;
    }
    __finally
    {
        if (m_Exitok != MAGIC_EXIT_NO)
            FaultHandler();
    }
}

I've used this in the past to do things like save backups of open files prior to exit. Certain JIT debugging settings will break this mechanism though.