为什么在这里需要这个花括号？ 谁能解释我为什么会这样？

Question

I'm making a code to make a screenshot and save it in a JPEG file type. I found this piece of code but I don't understand why it gives me an error when I remove curly braces after GdiplusStartup(&gdiplusToken, &gdiplusStartupInput, NULL); .

Full code:

void gdiscreen()
{
    using namespace Gdiplus;
    GdiplusStartupInput gdiplusStartupInput;
    ULONG_PTR gdiplusToken;
    GdiplusStartup(&gdiplusToken, &gdiplusStartupInput, NULL);
    {
        HDC scrdc, memdc;
        HBITMAP membit;
        scrdc = ::GetDC(0);
        int Height = GetSystemMetrics(SM_CYSCREEN);
        int Width = GetSystemMetrics(SM_CXSCREEN);
        memdc = CreateCompatibleDC(scrdc);
        membit = CreateCompatibleBitmap(scrdc, Width, Height);
        HBITMAP hOldBitmap = (HBITMAP)SelectObject(memdc, membit);
        BitBlt(memdc, 0, 0, Width, Height, scrdc, 0, 0, SRCCOPY);
        Gdiplus::Bitmap bitmap(membit, NULL);
        CLSID clsid;
        GetEncoderClsid(L"image/jpeg", &clsid);
        bitmap.Save(L"screen.jpeg", &clsid);
        SelectObject(memdc, hOldBitmap);
        DeleteObject(memdc);
        DeleteObject(membit);
        ::ReleaseDC(0, scrdc);
    }
    GdiplusShutdown(gdiplusToken);
}

Can somebody explain to me why I need the curly braces?

And when I remove the curly braces it gives me the following error:

Exception produced in 0x661AF6B8 (GdiPlus.dll) in DebugScreenShotModule.exe: 0xC0000005: Access violation when reading location 0x029E12AC.

Answer 1

You have a variable Gdiplus::Bitmap bitmap declared within the curly braces. It will be destroyed at the closing } . Without the curly braces, it won't be destroyed until after GdiplusShutdown is called.