The data types in this chapter are keywords that define the size and meaning of parameters and return values associated with functions for the Microsoft Windows operating system, version 3.1. The following table contains character, integer, and Boolean types; pointer types; and handles. The character, integer, and Boolean types are common to most C compilers. Most of the pointer-type names begin with a prefix of P, N (for near pointers), or LP (for long pointers). A near pointer accesses data within the current data segment, and a long pointer contains a 32-bit segment:offset value. A Windows application uses a handle to refer to a resource that has been loaded into memory. Windows provides access to these resources through internally maintained tables that contain individual entries for each handle. Each entry in the handle table contains the address of the resource and a means of identifying the resource type.
The Windows data types are defined in the following table:
| Type | Definition |
| ABORTPROC | 32-bit pointer to an AbortProc callback function. |
| ATOM | 16-bit value used as an atom handle. |
| BOOL | 16-bit Boolean value. |
| BYTE | 8-bit unsigned integer. Use LPBYTE to create 32-bit pointers. Use PBYTE to create pointers that match the compiler memory model. |
| CATCHBUF[9] | 18-byte buffer used by the Catch function. |
| COLORREF | 32-bit value used as a color value. |
| DLGPROC | 32-bit pointer to a dialog box procedure. |
| DWORD | 32-bit unsigned integer or a segment:offset address. Use LPDWORD to create 32-bit pointers. Use PDWORD to create pointers that match the compiler memory model. |
| FARPROC | 32-bit pointer to a function. |
| FNCALLBACK | 32-bit value identifying the DdeCallback function. Use PFNCALLBACK to create pointers that match the compiler memory model. |
| FONTENUMPROC | 32-bit pointer to an EnumFontsProc callback function. |
| GLOBALHANDLE | 16-bit value used as a handle to a global memory object. |
| GNOTIFYPROC | 32-bit pointer to a NotifyProc callback function. |
| GOBJENUMPROC | 32-bit pointer to a EnumObjectsProc callback function. |
| GRAYSTRINGPROC | 32-bit pointer to a GrayStringProc callback function. |
| HANDLE | 16-bit value used as a general handle. Use LPHANDLE to create 32-bit pointers. Use SPHANDLE to create 16-bit pointers. Use PHANDLE to create pointers that match the compiler memory model. |
| HCURSOR | 16-bit value used as a cursor handle. |
| HFILE | 16-bit value used as a file handle. |
| HGDIOBJ | 16-bit value used as a graphics device interface (GDI) object handle. |
| HGLOBAL | 16-bit value used as a handle to a global memory object. |
| HHOOK | 32-bit value used as a hook handle. |
| HKEY | 32-bit value used as a handle to a key in the registration database. Use PHKEY to create 32-bit pointers. |
| HLOCAL | 16-bit value used as a handle to a local memory object. |
| HMODULE | 16-bit value used as a module handle. |
| HOBJECT | 16-bit value used as a handle to an OLE object. |
| HWND | 16-bit value used as a handle to a window. |
| HOOKPROC | 32-bit pointer to a hook procedure. |
| HRSRC | 16-bit value used as a resource handle. |
| LHCLIENTDOC | 32-bit value used as a handle to an OLE client document. |
| LHSERVER | 32-bit value used as a handle to an OLE server. |
| LHSERVERDOC | 32-bit value used as a handle to an OLE server document. |
| LINEDDAPROC | 32-bit pointer to a LineDDAProc callback function. |
| LOCALHANDLE | 16-bit value used as a handle to a local memory object. |
| LONG | 32-bit signed integer. |
| LPABC | 32-bit pointer to an ABC structure. |
| LPARAM | 32-bit signed value passed as a parameter to a window procedure or callback function. |
| LPBI | 32-bit pointer to a BANDINFOSTRUCT structure. |
| LPBITMAP | 32-bit pointer to a BITMAP structure. Use NPBITMAP to create 16-bit pointers. Use PBITMAP to create pointers that match the compiler memory model. |
| LPBITMAPCOREHEADER | 32-bit pointer to a BITMAPCOREHEADER structure. Use PBITMAPCOREHEADER to create pointers that match the compiler memory model. |
| LPBITMAPCOREINFO | 32-bit pointer to a BITMAPCOREINFO structure. Use PBITMAPCOREINFO to create pointers that match the compiler memory model. |
| LPBITMAPFILEHEADER | 32-bit pointer to a BITMAPFILEHEADER structure. Use PBITMAPFILEHEADER to create pointers that match the compiler memory model. |
| LPBITMAPINFO | 32-bit pointer to a BITMAPINFO structure. Use PBITMAPINFO to create pointers that match the compiler memory model. |
| LPBITMAPINFOHEADER | 32-bit pointer to a BITMAPINFOHEADER structure. Use PBITMAPINFOHEADER to create pointers that match the compiler memory model. |
| LPCATCHBUF | 32-bit pointer to a CATCHBUF array. |
| LPCBT_CREATEWND | 32-bit pointer to a CBT_CREATEWND structure. |
| LPCHOOSECOLOR | 32-bit pointer to a CHOOSECOLOR structure. |
| LPCHOOSEFONT | 32-bit pointer to a CHOOSEFONT structure. |
| LPCLIENTCREATESTRUCT | 32-bit pointer to a CLIENTCREATESTRUCT structure. |
| LPCOMPAREITEMSTRUCT | 32-bit pointer to a COMPAREITEMSTRUCT structure. Use PCOMPAREITEMSTRUCT to create pointers that match the compiler memory model. |
| LPCPLINFO | 32-bit pointer to a CPLINFO structure. Use PCPLINFO to create pointers that match the compiler memory model. |
| LPCREATESTRUCT | 32-bit pointer to a CREATESTRUCT structure. |
| LPCSTR | 32-bit pointer to a nonmodifiable character string. |
| LPCTLINFO | 32-bit pointer to a CTLINFO structure. Use PCTLINFO to create pointers that match the compiler memory model. |
| LPCTLSTYLE | 32-bit pointer to a CTLSTYLE structure. Use PCTLSTYLE to create pointers that match the compiler memory model. |
| LPDCB | 32-bit pointer to a DCB structure. |
| LPDEBUGHOOKINFO | 32-bit pointer to a DEBUGHOOKINFO structure. |
| LPDELETEITEMSTRUCT | 32-bit pointer to a DELETEITEMSTRUCT structure. Use PDELETEITEMSTRUCT to create pointers that match the compiler memory model. |
| LPDEVMODE | 32-bit pointer to a DEVMODE structure. Use NPDEVMODE to create 16-bit pointers. Use PDEVMODE to create pointers that match the compiler memory model. |
| LPDEVNAMES | 32-bit pointer to a DEVNAMES structure. |
| LPDOCINFO | 32-bit pointer to a DOCINFO structure. |
| LPDRAWITEMSTRUCT | 32-bit pointer to a DRAWITEMSTRUCT structure. Use PDRAWITEMSTRUCT to create pointers that match the compiler memory model. |
| LPDRIVERINFOSTRUCT | 32-bit pointer to a DRIVERINFOSTRUCT structure. |
| LPDRVCONFIGINFO | 32-bit pointer to a DRVCONFIGINFO structure. Use PDRVCONFIGINFO to create pointers that match the compiler memory model. |
| LPEVENTMSG | 32-bit pointer to a EVENTMSG structure. Use NPEVENTMSG to create 16-bit pointers. Use PEVENTMSG to create pointers that match the compiler memory model. |
| LPDRIVERINFOSTRUCT | 32-bit pointer to a DRIVERINFOSTRUCT structure. |
| LPFINDREPLACE | 32-bit pointer to a FINDREPLACE structure. |
| LPFMS_GETDRIVEINFO | 32-bit pointer to a FMS_GETDRIVEINFO structure. |
| LPFMS_GETFILESEL | 32-bit pointer to a FMS_GETFILESEL structure. |
| LPFMS_LOAD | 32-bit pointer to a FMS_LOAD structure. |
| LPHANDLETABLE | 32-bit pointer to a HANDLETABLE structure. Use PHANDLETABLE to create pointers that match the compiler memory model. |
| LPHELPWININFO | 32-bit pointer to a HELPWININFO structure. Use PHELPWININFO to create pointers that match the compiler memory model. |
| LPINT | 32-bit pointer to a 16-bit signed value. Use PINT to create pointers that match the compiler memory model. |
| LPKERNINGPAIR | 32-bit pointer to a KERNINGPAIR structure. |
| LPLOGBRUSH | 32-bit pointer to a LOGBRUSH structure. Use NPLOGBRUSH to create 16-bit pointers. Use PLOGBRUSH to create pointers that match the compiler memory model. |
| LPLOGFONT | 32-bit pointer to a LOGFONT structure. Use NPLOGFONT to create 16-bit pointers. Use PLOGFONT to create pointers that match the compiler memory model. |
| LPLOGPALETTE | 32-bit pointer to a LOGPALETTE structure. Use NPLOGPALETTE to create 16-bit pointers. Use PLOGPALETTE to create pointers that match the compiler memory model. |
| LPLOGPEN | 32-bit pointer to a LOGPEN structure. Use NPLOGPEN to create 16-bit pointers. Use PLOGPEN to create pointers that match the compiler memory model. |
| LPLONG | 32-bit pointer to a 32-bit signed integer. Use PLONG to create pointers that match the compiler memory model. |
| LPMAT2 | 32-bit pointer to a MAT2 structure. |
| LPMDICREATESTRUCT | 32-bit pointer to an MDICREATESTRUCT structure. |
| LPMEASUREITEMSTRUCT | 32-bit pointer to a MEASUREITEMSTRUCT structure. Use PMEASUREITEMSTRUCT to create pointers that match the compiler memory model. |
| LPMETAFILEPICT | 32-bit pointer to a METAFILEPICT structure. |
| LPMETARECORD | 32-bit pointer to a METARECORD structure. Use PMETARECORD to create pointers that match the compiler memory model. |
| LPMOUSEHOOKSTRUCT | 32-bit pointer to a MOUSEHOOKSTRUCT structure. |
| LPMSG | 32-bit pointer to an MSG structure. Use NPMSG to create 16-bit pointers. Use PMSG to create pointers that match the compiler memory model. |
| LPNCCALCSIZE_PARAMS | 32-bit pointer to an NCCALCSIZE_PARAMS structure. |
| LPNEWCPLINFO | 32-bit pointer to an NEWCPLINFO structure. Use PNEWCPLINFO to create pointers that match the compiler memory model. |
| LPNEWTEXTMETRIC | 32-bit pointer to a NEWTEXTMETRIC structure. Use NPNEWTEXTMETRIC to create 16-bit pointers. Use PNEWTEXTMETRIC to create pointers that match the compiler memory model. |
| LPOFSTRUCT | 32-bit pointer to an OFSTRUCT structure. Use NPOFSTRUCT to create 16-bit pointers. Use POFSTRUCT to create pointers that match the compiler memory model. |
| LPOLECLIENT | 32-bit pointer to OLECLIENT structure. |
| LPOLECLIENTVTBL | 32-bit pointer to OLECLIENTVTBL structure. |
| LPOLEOBJECT | 32-bit pointer to OLEOBJECT structure. |
| LPOLEOBJECTVTBL | 32-bit pointer to OLEOBJECTVTBL structure. |
| LPOLESERVER | 32-bit pointer to OLESERVER structure. |
| LPOLESERVERDOC | 32-bit pointer to OLESERVERDOC structure. |
| LPOLESERVERDOCVTBL | 32-bit pointer to OLESERVERDOCVTBL structure. |
| LPOLESERVERVTBL | 32-bit pointer to OLESERVERVTBL structure. |
| LPOLESTREAM | 32-bit pointer to OLESTREAM structure. |
| LPOLESTREAMVTBL | 32-bit pointer to OLESTREAMVTBL structure. |
| LPOLETARGETDEVICE | 32-bit pointer to OLETARGETDEVICE structure. |
| LPOPENFILENAME | 32-bit pointer to OPENFILENAME structure. |
| LPOUTLINETEXTMETRIC | 32-bit pointer to an OUTLINETEXTMETRIC structure. |
| LPPAINTSTRUCT | 32-bit pointer to a PAINTSTRUCT structure. Use NPPAINTSTRUCT to create 16-bit pointers. Use PPAINTSTRUCT to create pointers that match the compiler memory model. |
| LPPALETTEENTRY | 32-bit pointer to a PALETTEENTRY structure. |
| LPPOINT | 32-bit pointer to a POINT structure. Use NPPOINT to create 16-bit pointers. Use PPOINT to create pointers that match the compiler memory model. |
| LPPOINTFX | 32-bit pointer to a POINTFX structure. |
| LPPRINTDLG | 32-bit pointer to a PRINTDLG structure. |
| LPRASTERIZER_STATUS | 32-bit pointer to a RASTERIZER_STATUS structure. |
| LPRECT | 32-bit pointer to a RECT structure. Use NPRECT to create 16-bit pointers. Use PRECT to create pointers that match the compiler memory model. |
| LPRGBQUAD | 32-bit pointer to a RGBQUAD structure. |
| LPRGBTRIPLE | 32-bit pointer to a RGBTRIPLE structure. |
| LPSEGINFO | 32-bit pointer to a SEGINFO structure. |
| LPSIZE | 32-bit pointer to a SIZE structure. Use NPSIZE to create 16-bit pointers. Use PSIZE to create pointers that match the compiler memory model. |
| LPSTR | 32-bit pointer to a character string. Use NPSTR to create 16-bit pointers. Use PSTR to create pointers that match the compiler memory model. |
| LPTEXTMETRIC | 32-bit pointer to a TEXTMETRIC structure. Use NPTEXTMETRIC to create 16-bit pointers. Use PTEXTMETRIC to create pointers that match the compiler memory model. |
| LPTTPOLYCURVE | 32-bit pointer to a TTPOLYCURVE structure. |
| LPTTPOLYGONHEADER | 32-bit pointer to a TTPOLYGONHEADER structure. |
| LPVOID | 32-bit pointer to an unspecified type. |
| LPWINDOWPLACEMENT | 32-bit pointer to a WINDOWPLACEMENT structure. Use PWINDOWPLACEMENT to create pointers that match the compiler memory model. |
| LPWINDOWPOS | 32-bit pointer to a WINDOWPOS structure. |
| LPWNDCLASS | 32-bit pointer to a WNDCLASS structure. Use NPWNDCLASS to create 16-bit pointers. Use PWNDCLASS to create pointers that match the compiler memory model. |
| LPWORD | 32-bit pointer to a 16-bit unsigned value. Use PWORD to create pointers that match the compiler memory model. |
| LRESULT | 32-bit signed value returned from a window procedure or callback function. |
| MFENUMPROC | 32-bit pointer to an EnumMetaFileProc callback function. |
| NEARPROC | 16-bit pointer to a function. |
| OLECLIPFORMAT | 16-bit value used as a standard clipboard format. |
| PATTERN | Equivalent to the LOGBRUSH structure. Use LPPATTERN to create 32-bit pointers. Use NPPATTERN to create 16-bit pointers. Use PPATTERN to create pointers that match the compiler memory model. |
| PCONVCONTEXT | 32-bit pointer to a CONVCONTEXT structure. |
| PCONVINFO | 32-bit pointer to a CONVINFO structure. |
| PHSZPAIR | 32-bit pointer to a HSZPAIR structure. |
| PROPENUMPROC | 32-bit pointer to an EnumPropFixedProc or EnumPropMovableProc callback function. |
| RSRCHDLRPROC | 32-bit pointer to a LoadProc callback function. |
| TIMERPROC | 32-bit pointer to a TimerProc callback function. |
| UINT | 16-bit unsigned value. |
| WNDENUMPROC | 32-bit pointer to an EnumWindowsProc callback function. |
| WNDPROC | 32-bit pointer to a window procedure. |
| WORD | 16-bit unsigned value. |
| WPARAM | 16-bit signed value passed as a parameter to a window procedure or callback function. |