Windows Data Types

The calling convention for system functions.

This type is declared in WinDef.h as follows:

#define APIENTRY WINAPI

An atom. For more information, see Atoms.

This type is declared in WinDef.h as follows:

typedef WORD ATOM;

A Boolean variable (should be TRUE or FALSE).

This type is declared in WinDef.h as follows:

typedef int BOOL;

A Boolean variable (should be TRUE or FALSE).

This type is declared in WinNT.h as follows:

typedef BYTE BOOLEAN;

A byte (8 bits).

This type is declared in WinDef.h as follows:

typedef unsigned char BYTE;

The calling convention for callback functions.

This type is declared in WinDef.h as follows:

#define CALLBACK __stdcall

CALLBACK, WINAPI, and APIENTRY are all used to define functions with the __stdcall calling convention. Most functions in the Windows API are declared using WINAPI. You may wish to use CALLBACK for the callback functions that you implement to help identify the function as a callback function.

An 8-bit Windows (ANSI) character. For more information, see Character Sets Used By Fonts.

This type is declared in WinNT.h as follows:

typedef char CHAR;

The red, green, blue (RGB) color value (32 bits). See COLORREF for information on this type.

This type is declared in WinDef.h as follows:

typedef DWORD COLORREF;

A variable whose value is to remain constant during execution.

This type is declared in WinDef.h as follows:

#define CONST const

A 32-bit unsigned integer. The range is 0 through 4294967295 decimal.

This type is declared in WinDef.h as follows:

typedef unsigned long DWORD;

A 64-bit unsigned integer. The range is 0 through 18446744073709551615 decimal.

This type is declared in WinNT.h as follows:

typedef ULONGLONG DWORDLONG;

An unsigned long type for pointer precision. Use when casting a pointer to a long type to perform pointer arithmetic. (Also commonly used for general 32-bit parameters that have been extended to 64 bits in 64-bit Windows.)

This type is declared in BaseTsd.h as follows:

typedef ULONG_PTR DWORD_PTR;

A 32-bit unsigned integer.

This type is declared in BaseTsd.h as follows:

typedef unsigned int DWORD32;

A 64-bit unsigned integer.

This type is declared in BaseTsd.h as follows:

typedef unsigned __int64 DWORD64;

A floating-point variable.

This type is declared in WinDef.h as follows:

typedef float FLOAT;

A handle to an accelerator table.

This type is declared in WinDef.h as follows:

typedef HANDLE HACCEL;

Half the size of a pointer. Use within a structure that contains a pointer and two small fields.

This type is declared in Basetsd.h as follows:

#ifdef _WIN64
 typedef int HALF_PTR;
#else
 typedef short HALF_PTR;
#endif

A handle to an object.

This type is declared in WinNT.h as follows:

typedef PVOID HANDLE;

A handle to a bitmap.

This type is declared in WinDef.h as follows:

typedef HANDLE HBITMAP;

A handle to a brush.

This type is declared in WinDef.h as follows:

typedef HANDLE HBRUSH;

A handle to a color space.

This type is declared in WinDef.h as follows:

typedef HANDLE HCOLORSPACE;

A handle to a dynamic data exchange (DDE) conversation.

This type is declared in Ddeml.h as follows:

typedef HANDLE HCONV;

A handle to a DDE conversation list.

This type is declared in Ddeml.h as follows:

typedef HANDLE HCONVLIST;

A handle to a cursor.

This type is declared in WinDef.h as follows:

typedef HICON HCURSOR;

A handle to a device context (DC).

This type is declared in WinDef.h as follows:

typedef HANDLE HDC;

A handle to DDE data.

This type is declared in Ddeml.h as follows:

typedef HANDLE HDDEDATA;

A handle to a desktop.

This type is declared in WinDef.h as follows:

typedef HANDLE HDESK;

A handle to an internal drop structure.

This type is declared in ShellApi.h as follows:

typedef HANDLE HDROP;

A handle to a deferred window position structure.

This type is declared in WinUser.h as follows:

typedef HANDLE HDWP;

A handle to an enhanced metafile.

This type is declared in WinDef.h as follows:

typedef HANDLE HENHMETAFILE;

A handle to a file opened by OpenFile, not CreateFile.

This type is declared in WinDef.h as follows:

typedef int HFILE;

A handle to a font.

This type is declared in WinDef.h as follows:

typedef HANDLE HFONT;

A handle to a GDI object.

This type is declared in WinDef.h as follows:

typedef HANDLE HGDIOBJ;

A handle to a global memory block.

This type is declared in WinDef.h as follows:

typedef HANDLE HGLOBAL;

A handle to a hook.

This type is declared in WinDef.h as follows:

typedef HANDLE HHOOK;

A handle to an icon.

This type is declared in WinDef.h as follows:

typedef HANDLE HICON;

A handle to an instance. This is the base address of the module in memory.

HMODULE and HINSTANCE are the same today, but represented different things in 16-bit Windows.

This type is declared in WinDef.h as follows:

typedef HANDLE HINSTANCE;

A handle to a registry key.

This type is declared in WinDef.h as follows:

typedef HANDLE HKEY;

An input locale identifier.

This type is declared in WinDef.h as follows:

typedef HANDLE HKL;

A handle to a local memory block.

This type is declared in WinDef.h as follows:

typedef HANDLE HLOCAL;

A handle to a menu.

This type is declared in WinDef.h as follows:

typedef HANDLE HMENU;

A handle to a metafile.

This type is declared in WinDef.h as follows:

typedef HANDLE HMETAFILE;

A handle to a module. The is the base address of the module in memory.

HMODULE and HINSTANCE are the same in current versions of Windows, but represented different things in 16-bit Windows.

This type is declared in WinDef.h as follows:

typedef HINSTANCE HMODULE;

A handle to a display monitor.

This type is declared in WinDef.h as follows:

if(WINVER >= 0x0500) typedef HANDLE HMONITOR;

A handle to a palette.

This type is declared in WinDef.h as follows:

typedef HANDLE HPALETTE;

A handle to a pen.

This type is declared in WinDef.h as follows:

typedef HANDLE HPEN;

The return codes used by COM interfaces. For more information, see Structure of the COM Error Codes. To test an HRESULT value, use the FAILED and SUCCEEDED macros.

This type is declared in WinNT.h as follows:

typedef LONG HRESULT;

A handle to a region.

This type is declared in WinDef.h as follows:

typedef HANDLE HRGN;

A handle to a resource.

This type is declared in WinDef.h as follows:

typedef HANDLE HRSRC;

A handle to a DDE string.

This type is declared in Ddeml.h as follows:

typedef HANDLE HSZ;

A handle to a window station.

This type is declared in WinDef.h as follows:

typedef HANDLE WINSTA;

A handle to a window.

This type is declared in WinDef.h as follows:

typedef HANDLE HWND;

A 32-bit signed integer. The range is -2147483648 through 2147483647 decimal.

This type is declared in WinDef.h as follows:

typedef int INT;

A signed integer type for pointer precision. Use when casting a pointer to an integer to perform pointer arithmetic.

This type is declared in BaseTsd.h as follows:

#if defined(_WIN64) 
 typedef __int64 INT_PTR; 
#else 
 typedef int INT_PTR;
#endif

A 32-bit signed integer. The range is -2147483648 through 2147483647 decimal.

This type is declared in BaseTsd.h as follows:

typedef signed int INT32;

A 64-bit signed integer. The range is –9223372036854775808 through 9223372036854775807 decimal.

This type is declared in BaseTsd.h as follows:

typedef signed __int64 INT64;

A language identifier. For more information, see Language Identifiers.

This type is declared in WinNT.h as follows:

typedef WORD LANGID;

A locale identifier. For more information, see Locale Identifiers.

This type is declared in WinNT.h as follows:

typedef DWORD LCID;

A locale information type. For a list, see Locale Information Constants.

This type is declared in WinNls.h as follows:

typedef DWORD LCTYPE;

A language group identifier. For a list, see EnumLanguageGroupLocales.

This type is declared in WinNls.h as follows:

typedef DWORD LGRPID;

A 32-bit signed integer. The range is –2147483648 through 2147483647 decimal.

This type is declared in WinNT.h as follows:

typedef long LONG;

A 64-bit signed integer. The range is –9223372036854775808 through 9223372036854775807 decimal.

This type is declared in WinNT.h as follows:

#if !defined(_M_IX86)
 typedef __int64 LONGLONG; 
#else
 typedef double LONGLONG;
#endif

A signed long type for pointer precision. Use when casting a pointer to a long to perform pointer arithmetic.

This type is declared in BaseTsd.h as follows:

#if defined(_WIN64)
 typedef __int64 LONG_PTR; 
#else
 typedef long LONG_PTR;
#endif

A 32-bit signed integer. The range is –2147483648 through 2147483647 decimal.

This type is declared in BaseTsd.h as follows:

typedef signed int LONG32;

A 64-bit signed integer. The range is –9223372036854775808 through 9223372036854775807 decimal.

This type is declared in BaseTsd.h as follows:

typedef __int64 LONG64;

A message parameter.

This type is declared in WinDef.h as follows:

typedef LONG_PTR LPARAM;

A pointer to a BOOL.

This type is declared in WinDef.h as follows:

typedef BOOL far *LPBOOL;

A pointer to a BYTE.

This type is declared in WinDef.h as follows:

typedef BYTE far *LPBYTE;

A pointer to a COLORREF value.

This type is declared in WinDef.h as follows:

typedef DWORD *LPCOLORREF;

A pointer to a constant null-terminated string of 8-bit Windows (ANSI) characters. For more information, see Character Sets Used By Fonts.

This type is declared in WinNT.h as follows:

typedef __nullterminated CONST CHAR *LPCSTR;

An LPCWSTR if UNICODE is defined, an LPCSTR otherwise. For more information, see Windows Data Types for Strings.

This type is declared in WinNT.h as follows:

#ifdef UNICODE
 typedef LPCWSTR LPCTSTR; 
#else
 typedef LPCSTR LPCTSTR;
#endif

A pointer to a constant of any type.

This type is declared in WinDef.h as follows:

typedef CONST void *LPCVOID;

A pointer to a constant null-terminated string of 16-bit Unicode characters. For more information, see Character Sets Used By Fonts.

This type is declared in WinNT.h as follows:

typedef CONST WCHAR *LPCWSTR;

A pointer to a DWORD.

This type is declared in WinDef.h as follows:

typedef DWORD *LPDWORD;

A pointer to a HANDLE.

This type is declared in WinDef.h as follows:

typedef HANDLE *LPHANDLE;

A pointer to an INT.

This type is declared in WinDef.h as follows:

typedef int *LPINT;

A pointer to a LONG.

This type is declared in WinDef.h as follows:

typedef long *LPLONG;

A pointer to a null-terminated string of 8-bit Windows (ANSI) characters. For more information, see Character Sets Used By Fonts.

This type is declared in WinNT.h as follows:

typedef CHAR *LPSTR;

An LPWSTR if UNICODE is defined, an LPSTR otherwise. For more information, see Windows Data Types for Strings.

This type is declared in WinNT.h as follows:

#ifdef UNICODE
 typedef LPWSTR LPTSTR;
#else
 typedef LPSTR LPTSTR;
#endif

A pointer to any type.

This type is declared in WinDef.h as follows:

typedef void *LPVOID;

A pointer to a WORD.

This type is declared in WinDef.h as follows:

typedef WORD *LPWORD;

A pointer to a null-terminated string of 16-bit Unicode characters. For more information, see Character Sets Used By Fonts.

This type is declared in WinNT.h as follows:

typedef WCHAR *LPWSTR;

Signed result of message processing.

This type is declared in WinDef.h as follows:

typedef LONG_PTR LRESULT;

A pointer to a BOOL.

This type is declared in WinDef.h as follows:

typedef BOOL *PBOOL;

A pointer to a BOOLEAN.

This type is declared in WinNT.h as follows:

typedef BOOLEAN *PBOOLEAN;

A pointer to a BYTE.

This type is declared in WinDef.h as follows:

typedef BYTE *PBYTE;

A pointer to a CHAR.

This type is declared in WinNT.h as follows:

typedef CHAR *PCHAR;

A pointer to a constant null-terminated string of 8-bit Windows (ANSI) characters. For more information, see Character Sets Used By Fonts.

This type is declared in WinNT.h as follows:

typedef CONST CHAR *PCSTR;

A PCWSTR if UNICODE is defined, a PCSTR otherwise. For more information, see Windows Data Types for Strings.

This type is declared in WinNT.h as follows:

#ifdef UNICODE
 typedef LPCWSTR PCTSTR;
#else
 typedef LPCSTR PCTSTR;
#endif

A pointer to a constant null-terminated string of 16-bit Unicode characters. For more information, see Character Sets Used By Fonts.

This type is declared in WinNT.h as follows:

typedef CONST WCHAR *PCWSTR;

A pointer to a DWORD.

This type is declared in WinDef.h as follows:

typedef DWORD *PDWORD;

A pointer to a DWORDLONG.

This type is declared in WinNT.h as follows:

typedef DWORDLONG *PDWORDLONG;

A pointer to a DWORD_PTR.

This type is declared in BaseTsd.h as follows:

typedef DWORD_PTR *PDWORD_PTR;

A pointer to a DWORD32.

This type is declared in BaseTsd.h as follows:

typedef DWORD32 *PDWORD32;

A pointer to a DWORD64.

This type is declared in BaseTsd.h as follows:

typedef DWORD64 *PDWORD64;

A pointer to a FLOAT.

This type is declared in WinDef.h as follows:

typedef FLOAT *PFLOAT;

A pointer to a HALF_PTR.

This type is declared in Basetsd.h as follows:

#ifdef _WIN64
 typedef HALF_PTR *PHALF_PTR;
#else
 typedef HALF_PTR *PHALF_PTR;
#endif

A pointer to a HANDLE.

This type is declared in WinNT.h as follows:

typedef HANDLE *PHANDLE;

A pointer to an HKEY.

This type is declared in WinDef.h as follows:

typedef HKEY *PHKEY;

A pointer to an INT.

This type is declared in WinDef.h as follows:

typedef int *PINT;

A pointer to an INT_PTR.

This type is declared in BaseTsd.h as follows:

typedef INT_PTR *PINT_PTR;

A pointer to an INT32.

This type is declared in BaseTsd.h as follows:

typedef INT32 *PINT32;

A pointer to an INT64.

This type is declared in BaseTsd.h as follows:

typedef INT64 *PINT64;

A pointer to an LCID.

This type is declared in WinNT.h as follows:

typedef PDWORD PLCID;

A pointer to a LONG.

This type is declared in WinNT.h as follows:

typedef LONG *PLONG;

A pointer to a LONGLONG.

This type is declared in WinNT.h as follows:

typedef LONGLONG *PLONGLONG;

A pointer to a LONG_PTR.

This type is declared in BaseTsd.h as follows:

typedef LONG_PTR *PLONG_PTR;

A pointer to a LONG32.

This type is declared in BaseTsd.h as follows:

typedef LONG32 *PLONG32;

A pointer to a LONG64.

This type is declared in BaseTsd.h as follows:

typedef LONG64 *PLONG64;

A 32-bit pointer. On a 32-bit system, this is a native pointer. On a 64-bit system, this is a truncated 64-bit pointer.

This type is declared in BaseTsd.h as follows:

#if defined(_WIN64)
 #define POINTER_32 __ptr32
#else
 #define POINTER_32
#endif

A 64-bit pointer. On a 64-bit system, this is a native pointer. On a 32-bit system, this is a sign-extended 32-bit pointer.

Note that it is not safe to assume the state of the high pointer bit.

This type is declared in BaseTsd.h as follows:

#if (_MSC_VER >= 1300)
 #define POINTER_64 __ptr64
#else
 #define POINTER_64
#endif

A signed pointer.

This type is declared in BaseTsd.h as follows:

#define POINTER_SIGNED __sptr

An unsigned pointer.

This type is declared in BaseTsd.h as follows:

#define POINTER_UNSIGNED __uptr

A pointer to a SHORT.

This type is declared in WinNT.h as follows:

typedef SHORT *PSHORT;

A pointer to a SIZE_T.

This type is declared in BaseTsd.h as follows:

typedef SIZE_T *PSIZE_T;

A pointer to a SSIZE_T.

This type is declared in BaseTsd.h as follows:

typedef SSIZE_T *PSSIZE_T;

A pointer to a null-terminated string of 8-bit Windows (ANSI) characters. For more information, see Character Sets Used By Fonts.

This type is declared in WinNT.h as follows:

typedef CHAR *PSTR;

A pointer to a TBYTE.

This type is declared in WinNT.h as follows:

typedef TBYTE *PTBYTE;

A pointer to a TCHAR.

This type is declared in WinNT.h as follows:

typedef TCHAR *PTCHAR;

A PWSTR if UNICODE is defined, a PSTR otherwise. For more information, see Windows Data Types for Strings.

This type is declared in WinNT.h as follows:

#ifdef UNICODE
 typedef LPWSTR PTSTR;
#else typedef LPSTR PTSTR;
#endif

A pointer to a UCHAR.

This type is declared in WinDef.h as follows:

typedef UCHAR *PUCHAR;

A pointer to a UHALF_PTR.

This type is declared in Basetsd.h as follows:

#ifdef _WIN64
 typedef UHALF_PTR *PUHALF_PTR;
#else
 typedef UHALF_PTR *PUHALF_PTR;
#endif

A pointer to a UINT.

This type is declared in WinDef.h as follows:

typedef UINT *PUINT;

A pointer to a UINT_PTR.

This type is declared in BaseTsd.h as follows:

typedef UINT_PTR *PUINT_PTR;

A pointer to a UINT32.

This type is declared in BaseTsd.h as follows:

typedef UINT32 *PUINT32;

A pointer to a UINT64.

This type is declared in BaseTsd.h as follows:

typedef UINT64 *PUINT64;

A pointer to a ULONG.

This type is declared in WinDef.h as follows:

typedef ULONG *PULONG;

A pointer to a ULONGLONG.

This type is declared in WinDef.h as follows:

typedef ULONGLONG *PULONGLONG;

A pointer to a ULONG_PTR.

This type is declared in BaseTsd.h as follows:

typedef ULONG_PTR *PULONG_PTR;

A pointer to a ULONG32.

This type is declared in BaseTsd.h as follows:

typedef ULONG32 *PULONG32;

A pointer to a ULONG64.

This type is declared in BaseTsd.h as follows:

typedef ULONG64 *PULONG64;

A pointer to a USHORT.

This type is declared in WinDef.h as follows:

typedef USHORT *PUSHORT;

A pointer to any type.

This type is declared in WinNT.h as follows:

typedef void *PVOID;

A pointer to a WCHAR.

This type is declared in WinNT.h as follows:

typedef WCHAR *PWCHAR;

A pointer to a WORD.

This type is declared in WinDef.h as follows:

typedef WORD *PWORD;

A pointer to a null-terminated string of 16-bit Unicode characters. For more information, see Character Sets Used By Fonts.

This type is declared in WinNT.h as follows:

typedef WCHAR *PWSTR;

A handle to a service control manager database. For more information, see SCM Handles.

This type is declared in WinSvc.h as follows:

typedef HANDLE SC_HANDLE;

A lock to a service control manager database. For more information, see SCM Handles.

This type is declared in WinSvc.h as follows:

typedef LPVOID SC_LOCK;

A handle to a service status value. For more information, see SCM Handles.

This type is declared in WinSvc.h as follows:

typedef HANDLE SERVICE_STATUS_HANDLE;

A 16-bit integer. The range is –32768 through 32767 decimal.

This type is declared in WinNT.h as follows:

typedef short SHORT;

The maximum number of bytes to which a pointer can point. Use for a count that must span the full range of a pointer.

This type is declared in BaseTsd.h as follows:

typedef ULONG_PTR SIZE_T;

A signed version of SIZE_T.

This type is declared in BaseTsd.h as follows:

typedef LONG_PTR SSIZE_T;

A WCHAR if UNICODE is defined, a CHAR otherwise.

This type is declared in WinNT.h as follows:

#ifdef UNICODE
 typedef WCHAR TBYTE;
#else
 typedef unsigned char TBYTE;
#endif

A WCHAR if UNICODE is defined, a CHAR otherwise.

This type is declared in WinNT.h as follows:

#ifdef UNICODE
 typedef WCHAR TCHAR;
#else
 typedef char TCHAR;
#endif

An unsigned CHAR.

This type is declared in WinDef.h as follows:

typedef unsigned char UCHAR;

An unsigned HALF_PTR. Use within a structure that contains a pointer and two small fields.

This type is declared in Basetsd.h as follows:

#ifdef _WIN64
 typedef unsigned int UHALF_PTR;
#else
 typedef unsigned short UHALF_PTR;
#endif

An unsigned INT. The range is 0 through 4294967295 decimal.

This type is declared in WinDef.h as follows:

typedef unsigned int UINT;

An unsigned INT_PTR.

This type is declared in BaseTsd.h as follows:

#if defined(_WIN64)
 typedef unsigned __int64 UINT_PTR;
#else
 typedef unsigned int UINT_PTR;
#endif

An unsigned INT32. The range is 0 through 4294967295 decimal.

This type is declared in BaseTsd.h as follows:

typedef unsigned int UINT32;

An unsigned INT64. The range is 0 through 18446744073709551615 decimal.

This type is declared in BaseTsd.h as follows:

typedef usigned __int 64 UINT64;

An unsigned LONG. The range is 0 through 4294967295 decimal.

This type is declared in WinDef.h as follows:

typedef unsigned long ULONG;

A 64-bit unsigned integer. The range is 0 through 18446744073709551615 decimal.

This type is declared in WinNT.h as follows:

#if !defined(_M_IX86)
 typedef unsigned __int64 ULONGLONG;
#else
 typedef double ULONGLONG;
#endif

An unsigned LONG_PTR.

This type is declared in BaseTsd.h as follows:

#if defined(_WIN64)
 typedef unsigned __int64 ULONG_PTR;
#else
 typedef unsigned long ULONG_PTR;
#endif

An unsigned LONG32. The range is 0 through 4294967295 decimal.

This type is declared in BaseTsd.h as follows:

typedef unsigned int ULONG32;

An unsigned LONG64. The range is 0 through 18446744073709551615 decimal.

This type is declared in BaseTsd.h as follows:

typedef unsigned __int64 ULONG64;

A Unicode string.

This type is declared in Winternl.h as follows:

typedef struct _UNICODE_STRING {
  USHORT  Length;
  USHORT  MaximumLength;
  PWSTR  Buffer;
} UNICODE_STRING;
typedef UNICODE_STRING *PUNICODE_STRING;
typedef const UNICODE_STRING *PCUNICODE_STRING;

An unsigned SHORT. The range is 0 through 65535 decimal.

This type is declared in WinDef.h as follows:

typedef unsigned short USHORT;

An update sequence number (USN).

This type is declared in WinNT.h as follows:

typedef LONGLONG USN;

Any type.

This type is declared in WinNT.h as follows:

#define VOID void

A 16-bit Unicode character. For more information, see Character Sets Used By Fonts.

This type is declared in WinNT.h as follows:

typedef wchar_t WCHAR;

The calling convention for system functions.

This type is declared in WinDef.h as follows:

#define WINAPI __stdcall

CALLBACK, WINAPI, and APIENTRY are all used to define functions with the __stdcall calling convention. Most functions in the Windows API are declared using WINAPI. You may wish to use CALLBACK for the callback functions that you implement to help identify the function as a callback function.

A 16-bit unsigned integer. The range is 0 through 65535 decimal.

This type is declared in WinDef.h as follows:

typedef unsigned short WORD;

A message parameter.

This type is declared in WinDef.h as follows:

typedef UINT_PTR WPARAM;