Question

I am trying to use MFC with visual Studio 2012 on Windows 8.
I have the following code:

BOOL CALLBACK EWP(HWND hwnd, LPARAM lParam)
{
    int txtlen = GetWindowTextLengthW(hwnd);
    std::wstring s;
    s.reserve(txtlen + 1);
    GetWindowText(hwnd, const_cast<wchar_t*>(s.c_str()), txtlen);

    return TRUE;
}

EnumWindows(EWP, 0);

What happens is that the very first string comes out as “Task Switchin” and the rest come out as “”. I get about 330 of these strings. I have tried without using that weird string method too with just char buff[300], same story.

Can someone please tell me whats going on?

Answer 1

Your last argument to GetWindowText() is off-by-one. From the MSDN article description of that argument:

Specifies the maximum number of characters to copy to the buffer, including the NULL character. If the text exceeds this limit, it is truncated.

Pass txtlen+1 to fix.