自学教程：C++ zerostruct函数代码示例

    static std::tm millisToUTC (int64 millis) noexcept    {       #if JUCE_WINDOWS && JUCE_MINGW        time_t now = (time_t) (millis / 1000);        return *gmtime (&now);       #elif JUCE_WINDOWS        std::tm result;        millis /= 1000;        if (_gmtime64_s (&result, &millis) != 0)            zerostruct (result);        return result;       #else        std::tm result;        time_t now = (time_t) (millis / 1000);        if (gmtime_r (&now, &result) == nullptr)            zerostruct (result);        return result;       #endif    }

ID3D11ShaderResourceView* D3D11Context::createShaderResourceView (ID3D11Texture2D* texture, DXGI_FORMAT srvFormat){    D3D11_TEXTURE2D_DESC texdesc;    texture->GetDesc (&texdesc);    D3D11_SHADER_RESOURCE_VIEW_DESC desc;    zerostruct (desc);    if (-1 == srvFormat)        desc.Format = texdesc.Format;    else        desc.Format = srvFormat;    if (1 == texdesc.ArraySize)    {        desc.ViewDimension = D3D11_SRV_DIMENSION_TEXTURE2D;        desc.Texture2D.MipLevels = texdesc.MipLevels;        desc.Texture2D.MostDetailedMip = 0;    }    else    {        desc.ViewDimension = D3D11_SRV_DIMENSION_TEXTURE2DARRAY;        desc.Texture2DArray.ArraySize = texdesc.ArraySize;        desc.Texture2DArray.FirstArraySlice = 0;        desc.Texture2DArray.MipLevels = texdesc.MipLevels;        desc.Texture2DArray.MostDetailedMip = 0;    }    Hold<ID3D11ShaderResourceView> srview;    if (m_failed (device->CreateShaderResourceView (texture, &desc, srview)))        return nullptr;    return srview.drop();}

//==============================================================================void VstPluginExternalEditor::mouseExit (const MouseEvent& e){#if defined(LINUX)    if (! handle) return;    XEvent ev;    zerostruct (ev);    ev.xcrossing.display = display;    ev.xcrossing.type = LeaveNotify;    ev.xcrossing.window = handle;    ev.xcrossing.root = RootWindow (display, DefaultScreen (display));    ev.xcrossing.time = CurrentTime;    ev.xcrossing.x = e.x;    ev.xcrossing.y = e.y;    ev.xcrossing.x_root = e.getScreenX ();    ev.xcrossing.y_root = e.getScreenY ();    ev.xcrossing.mode = NotifyNormal; // NotifyGrab, NotifyUngrab    ev.xcrossing.detail = NotifyAncestor; // NotifyVirtual, NotifyInferior, NotifyNonlinear,NotifyNonlinearVirtual    ev.xcrossing.focus = hasKeyboardFocus (true); // TODO - yes ?    translateJuceToXCrossingModifiers (e, ev);    sendEventToChild (& ev);#endif}

void AudioPlayHead::CurrentPositionInfo::resetToDefault(){    zerostruct (*this);    timeSigNumerator = 4;    timeSigDenominator = 4;    bpm = 120;}

    Pimpl (SystemTrayIconComponent& owner_, HICON hicon, HWND hwnd)        : owner (owner_),          originalWndProc ((WNDPROC) GetWindowLongPtr (hwnd, GWLP_WNDPROC)),          taskbarCreatedMessage (RegisterWindowMessage (TEXT ("TaskbarCreated")))    {        SetWindowLongPtr (hwnd, GWLP_WNDPROC, (LONG_PTR) hookedWndProc);        zerostruct (iconData);        iconData.cbSize = sizeof (iconData);        iconData.hWnd = hwnd;        iconData.uID = (UINT) (pointer_sized_int) hwnd;        iconData.uFlags = NIF_ICON | NIF_MESSAGE | NIF_TIP;        iconData.uCallbackMessage = WM_TRAYNOTIFY;        iconData.hIcon = hicon;        Shell_NotifyIcon (NIM_ADD, &iconData);        // In order to receive the "TaskbarCreated" message, we need to request that it's not filtered out.        // (Need to load dynamically, as ChangeWindowMessageFilter is only available in Vista and later)        typedef BOOL (WINAPI* ChangeWindowMessageFilterType) (UINT, DWORD);        ChangeWindowMessageFilterType changeWindowMessageFilter            = (ChangeWindowMessageFilterType) getUser32Function ("ChangeWindowMessageFilter");        if (changeWindowMessageFilter != nullptr)            changeWindowMessageFilter (taskbarCreatedMessage, 1 /* MSGFLT_ADD */);    }

void VstPluginExternalEditor::updateWindowPosition (const int x, const int y){#if defined(LINUX)    if (! handle) return;    XEvent ev;    zerostruct (ev);    ev.xgravity.type = GravityNotify;    ev.xgravity.display = display;    ev.xgravity.window = handle;    ev.xgravity.event = (Window) window->getWindowHandle ();    ev.xgravity.x = x;    ev.xgravity.y = y;    // DBG ("Window Position Updated to: " + String (x) + " " + String (y));    sendEventToChild (& ev);#endif    //#ifdef JUCE_MAC#if 0    if (vstGuiWindow)        vstGuiWindow->setTopLeftPosition(window->getX() + offsetX, window->getY() + offsetY);#endif}

const StringArray Font::findAllTypefaceNames(){    StringArray results;    HDC dc = CreateCompatibleDC (0);    {        LOGFONTW lf;        zerostruct (lf);        lf.lfWeight = FW_DONTCARE;        lf.lfOutPrecision = OUT_OUTLINE_PRECIS;        lf.lfQuality = DEFAULT_QUALITY;        lf.lfCharSet = DEFAULT_CHARSET;        lf.lfClipPrecision = CLIP_DEFAULT_PRECIS;        lf.lfPitchAndFamily = FF_DONTCARE;        lf.lfFaceName[0] = 0;        EnumFontFamiliesEx (dc, &lf,                            (FONTENUMPROCW) &wfontEnum1,                            (LPARAM) &results, 0);    }    DeleteDC (dc);    results.sort (true);    return results;}

            void childBoundsChanged (juce::Component* child)            {                setSize (child->getWidth(), child->getHeight());                child->setTopLeftPosition (0, 0);#if JUCE_WIN32                resizeHostWindow (hostWindow, titleW, titleH, this);                owner->updateSize();#else                Rect r;                GetWindowBounds ((WindowRef) hostWindow, kWindowContentRgn, &r);                HIRect p;                zerostruct (p);                HIViewConvertRect (&p, parentView, 0); // find the X position of our view in case there's space to the left of it                r.right = r.left + jmax (titleW, ((int) p.origin.x) + getWidth());                r.bottom = r.top + getHeight() + titleH;                SetWindowBounds ((WindowRef) hostWindow, kWindowContentRgn, &r);                owner->updateSize();                owner->Invalidate();#endif            }

static int CALLBACK wfontEnum1 (ENUMLOGFONTEXW* lpelfe,                                NEWTEXTMETRICEXW*,                                int type,                                LPARAM lParam){    if (lpelfe != 0 && (type & RASTER_FONTTYPE) == 0)    {        LOGFONTW lf;        zerostruct (lf);        lf.lfWeight = FW_DONTCARE;        lf.lfOutPrecision = OUT_OUTLINE_PRECIS;        lf.lfQuality = DEFAULT_QUALITY;        lf.lfCharSet = DEFAULT_CHARSET;        lf.lfClipPrecision = CLIP_DEFAULT_PRECIS;        lf.lfPitchAndFamily = FF_DONTCARE;        const String fontName (lpelfe->elfLogFont.lfFaceName);        fontName.copyToUnicode (lf.lfFaceName, LF_FACESIZE - 1);        HDC dc = CreateCompatibleDC (0);        EnumFontFamiliesEx (dc, &lf,                            (FONTENUMPROCW) &wfontEnum2,                            lParam, 0);        DeleteDC (dc);    }    return 1;}

MD5::MD5 (const File& file){    FileInputStream fin (file);    if (fin.getStatus().wasOk())        processStream (fin, -1);    else        zerostruct (result);}

    JUCE_COMRESULT Stat (STATSTG* stat, DWORD)    {        if (stat == nullptr)            return STG_E_INVALIDPOINTER;        zerostruct (*stat);        stat->type = STGTY_STREAM;        stat->cbSize.QuadPart = jmax ((int64) 0, source.getTotalLength());        return S_OK;    }

BEGIN_JUCE_NAMESPACE#include "juce_MD5.h"#include "../io/files/juce_FileInputStream.h"//==============================================================================MD5::MD5(){    zerostruct (result);}

BEGIN_JUCE_NAMESPACE#include "juce_MidiKeyboardState.h"#include "../../core/juce_Time.h"//==============================================================================MidiKeyboardState::MidiKeyboardState(){    zerostruct (noteStates);}

    struct tm  millisToLocal (const int64 millis) noexcept    {        struct tm result;        const int64 seconds = millis / 1000;        if (seconds < literal64bit (86400) || seconds >= literal64bit (2145916800))        {            // use extended maths for dates beyond 1970 to 2037..            const int timeZoneAdjustment = 31536000 - (int) (Time (1971, 0, 1, 0, 0).toMilliseconds() / 1000);            const int64 jdm = seconds + timeZoneAdjustment + literal64bit (210866803200);            const int days = (int) (jdm / literal64bit (86400));            const int a = 32044 + days;            const int b = (4 * a + 3) / 146097;            const int c = a - (b * 146097) / 4;            const int d = (4 * c + 3) / 1461;            const int e = c - (d * 1461) / 4;            const int m = (5 * e + 2) / 153;            result.tm_mday  = e - (153 * m + 2) / 5 + 1;            result.tm_mon   = m + 2 - 12 * (m / 10);            result.tm_year  = b * 100 + d - 6700 + (m / 10);            result.tm_wday  = (days + 1) % 7;            result.tm_yday  = -1;            int t = (int) (jdm % literal64bit (86400));            result.tm_hour  = t / 3600;            t %= 3600;            result.tm_min   = t / 60;            result.tm_sec   = t % 60;            result.tm_isdst = -1;        }        else        {            time_t now = static_cast <time_t> (seconds);          #if JUCE_WINDOWS           #ifdef USE_NEW_SECURE_TIME_FNS            if (now >= 0 && now <= 0x793406fff)                localtime_s (&result, &now);            else                zerostruct (result);           #else            result = *localtime (&now);           #endif          #else            localtime_r (&now, &result); // more thread-safe          #endif        }        return result;    }

    static bool bindSocketToPort (const SocketHandle handle, const int port) noexcept    {        if (handle <= 0 || port <= 0)            return false;        struct sockaddr_in servTmpAddr;        zerostruct (servTmpAddr); // (can't use "= { 0 }" on this object because it's typedef'ed as a C struct)        servTmpAddr.sin_family = PF_INET;        servTmpAddr.sin_addr.s_addr = htonl (INADDR_ANY);        servTmpAddr.sin_port = htons ((uint16) port);        return bind (handle, (struct sockaddr*) &servTmpAddr, sizeof (struct sockaddr_in)) >= 0;    }

static bool bindSocketToPort (const int handle, const int port) throw(){    if (handle <= 0 || port <= 0)        return false;    struct sockaddr_in servTmpAddr;    zerostruct (servTmpAddr);    servTmpAddr.sin_family = PF_INET;    servTmpAddr.sin_addr.s_addr = htonl (INADDR_ANY);    servTmpAddr.sin_port = htons ((uint16) port);    return bind (handle, (struct sockaddr*) &servTmpAddr, sizeof (struct sockaddr_in)) >= 0;}

//==============================================================================String SystemStats::getStackBacktrace(){    String result;   #if JUCE_ANDROID || JUCE_MINGW || JUCE_HAIKU    jassertfalse; // sorry, not implemented yet!   #elif JUCE_WINDOWS    HANDLE process = GetCurrentProcess();    SymInitialize (process, nullptr, TRUE);    void* stack[128];    int frames = (int) CaptureStackBackTrace (0, numElementsInArray (stack), stack, nullptr);    HeapBlock<SYMBOL_INFO> symbol;    symbol.calloc (sizeof (SYMBOL_INFO) + 256, 1);    symbol->MaxNameLen = 255;    symbol->SizeOfStruct = sizeof (SYMBOL_INFO);    for (int i = 0; i < frames; ++i)    {        DWORD64 displacement = 0;        if (SymFromAddr (process, (DWORD64) stack[i], &displacement, symbol))        {            result << i << ": ";            IMAGEHLP_MODULE64 moduleInfo;            zerostruct (moduleInfo);            moduleInfo.SizeOfStruct = sizeof (moduleInfo);            if (::SymGetModuleInfo64 (process, symbol->ModBase, &moduleInfo))                result << moduleInfo.ModuleName << ": ";            result << symbol->Name << " + 0x" << String::toHexString ((int64) displacement) << newLine;        }    }   #else    void* stack[128];    int frames = backtrace (stack, numElementsInArray (stack));    char** frameStrings = backtrace_symbols (stack, frames);    for (int i = 0; i < frames; ++i)        result << frameStrings[i] << newLine;    ::free (frameStrings);   #endif    return result;}

    static addrinfo* getAddressInfo (const bool isDatagram, const String& hostName, int portNumber)    {        struct addrinfo hints;        zerostruct (hints);        hints.ai_family = AF_UNSPEC;        hints.ai_socktype = isDatagram ? SOCK_DGRAM : SOCK_STREAM;        hints.ai_flags = AI_NUMERICSERV;        struct addrinfo* info = nullptr;        if (getaddrinfo (hostName.toUTF8(), String (portNumber).toUTF8(), &hints, &info) == 0)            return info;        return nullptr;    }

    static bool bindSocket (SocketHandle handle, int port, const String& address) noexcept    {        if (handle <= 0 || ! isValidPortNumber (port))            return false;        struct sockaddr_in addr;        zerostruct (addr); // (can't use "= { 0 }" on this object because it's typedef'ed as a C struct)        addr.sin_family = PF_INET;        addr.sin_port = htons ((uint16) port);        addr.sin_addr.s_addr = address.isNotEmpty() ? ::inet_addr (address.toRawUTF8())                                                    : htonl (INADDR_ANY);        return ::bind (handle, (struct sockaddr*) &addr, sizeof (addr)) >= 0;    }

    static bool multicast (int handle, const String& multicastIPAddress,                           const String& interfaceIPAddress, bool join) noexcept    {        struct ip_mreq mreq;        zerostruct (mreq);        mreq.imr_multiaddr.s_addr = inet_addr (multicastIPAddress.toUTF8());        mreq.imr_interface.s_addr = INADDR_ANY;        if (interfaceIPAddress.isNotEmpty())            mreq.imr_interface.s_addr = inet_addr (interfaceIPAddress.toUTF8());        int joinCmd = join ? IP_ADD_MEMBERSHIP : IP_DROP_MEMBERSHIP;        return setsockopt (handle, IPPROTO_IP, joinCmd, (const char*) &mreq, sizeof (mreq)) == 0;    }

    static bool bindSocket (const SocketHandle handle, const int port, const String& address) noexcept    {        if (handle <= 0 || port < 0)            return false;        struct sockaddr_in servTmpAddr;        zerostruct (servTmpAddr); // (can't use "= { 0 }" on this object because it's typedef'ed as a C struct)        servTmpAddr.sin_family = PF_INET;        servTmpAddr.sin_addr.s_addr = htonl (INADDR_ANY);        servTmpAddr.sin_port = htons ((uint16) port);       #if JUCE_WINDOWS        if (address.isNotEmpty())            servTmpAddr.sin_addr.s_addr = ::inet_addr (address.toUTF8());       #else        ignoreUnused (address);       #endif        return bind (handle, (struct sockaddr*) &servTmpAddr, sizeof (struct sockaddr_in)) >= 0;    }

//==============================================================================bool StreamingSocket::createListener (const int newPortNumber, const String& localHostName){    if (connected)        close();    hostName = "listener";    portNumber = newPortNumber;    isListener = true;    struct sockaddr_in servTmpAddr;    zerostruct (servTmpAddr);    servTmpAddr.sin_family = PF_INET;    servTmpAddr.sin_addr.s_addr = htonl (INADDR_ANY);	if (localHostName.isNotEmpty())	{		inet_pton(PF_INET, localHostName.toUTF8(), &servTmpAddr.sin_addr);		//servTmpAddr.sin_addr.s_addr = ::inet_addr(localHostName.toUTF8());	}    servTmpAddr.sin_port = htons ((uint16) portNumber);    handle = (int) socket (AF_INET, SOCK_STREAM, 0);    if (handle < 0)        return false;    const int reuse = 1;    setsockopt (handle, SOL_SOCKET, SO_REUSEADDR, (const char*) &reuse, sizeof (reuse));    if (bind (handle, (struct sockaddr*) &servTmpAddr, sizeof (struct sockaddr_in)) < 0         || listen (handle, SOMAXCONN) < 0)    {        close();        return false;    }    connected = true;    return true;}