Standard types

The Microsoft run-time library defines the following standard types and typedefs.

Fixed-width integral types (stdint.h)

Name	Equivalent built-in type
int8_t, uint8_t	signed char, unsigned char
int16_t, uint16_t	short, unsigned short
int32_t, uint32_t	int, unsigned int
int64_t, uint64_t	long long, unsigned long long
int_least8_t, uint_least8_t	signed char, unsigned char
int_least16_t, uint_least16_t	short, unsigned short
int_least32_t, uint_least32_t	int, unsigned int
int_least64_t, uint_least64_t	long long, unsigned long long
int_fast8_t, uint_fast8_t	signed char, unsigned char
int_fast16_t, uint_fast16_t	int, unsigned int
int_fast32_t, uint_fast32_t	int, unsigned int
int_fast64_t, uint_fast64_t	long long, unsigned long long
intmax_t, uintmax_t	long long, unsigned long long

Type	Description	Declared in
clock_t (long)	Stores time values; used by clock.	TIME.H
_complex structure	Stores real and imaginary parts of complex numbers; used by _cabs.	MATH.H
_CRT_ALLOC_HOOK	A type definition for the user-defined hook function. Used in _CrtSetAllocHook.	CRTDBG.H
_CRT_DUMP_CLIENT, _CRT_DUMP_CLIENT_M	A type definition for a call-back function that will get called in _CrtMemDumpAllObjectsSince.	CRTDBG.H
_CrtMemState structure	Provides information about the current state of the C run-time debug heap.	CRTDBG.H
_CRT_REPORT_HOOK, _CRT_REPORT_HOOKW, _CRT_REPORT_HOOKW_M	A type definition for a call-back function that will get called in _CrtDbgReport. The parameters for this function are: report type, output message and the return value from the call-back function.	CRTDBG.H
dev_t, _dev_t short or unsigned integer	Represents device handles.	SYS\TYPES.H
_diskfree_t structure	Contains information about a disk drive. Used by _getdiskfree.	DOS.H and DIRECT.H
div_t, ldiv_t and lldiv_t structures	Store values returned by div, ldiv, and lldiv, respectively.	STDLIB.H
errno_t integer	Used for a function return type or parameter that deals with the error codes of errno.	STDDEF.H, CRTDEFS.H
_exception structure	Stores error information for _matherr.	MATH.H
_EXCEPTION_POINTERS	Contains an exception record. For more information, see EXCEPTION_POINTERS.	FPIEEE.H
FILE structure	Stores information about current state of stream; used in all stream I/O operations.	STDIO.H
_finddata_t, _wfinddata_t, _finddata32_t, _wfinddata32_t, _finddatai64_t, _wfinddatai64_t, __finddata64_t, _wfinddata64_t, __finddata32i64_t, __wfinddata32i64_t, __finddata64i32_t, __wfinddata64i32_t structures	Store file-attribute information returned by _findfirst, _wfindfirst, and related functions and _findnext, _wfindnext and related functions. See Filename search functions for information on structure members.	IO.H, WCHAR.H
_FPIEEE_RECORD structure	Contains information pertaining to IEEE floating-point exception; passed to user-defined trap handler by _fpieee_flt.	FPIEEE.H
fpos_t (long integer, __int64, or structure, depending on the target platform)	Used by fgetpos and fsetpos to record information for uniquely specifying every position within a file.	STDIO.H
_fsize_t (unsigned long integer)	Used to represent the size of a file.	IO.H, WCHAR.H
_HEAPINFO structure	Contains information about next heap entry for _heapwalk.	MALLOC.H
_HFILE (void *)	An operating system file handle.	CRTDBG.H
imaxdiv_t	The type of value that's returned by the imaxdiv function, containing both the quotient and the remainder.	inttypes.h
ino_t, _ino_t (unsigned short)	For returning status information.	WCHAR.H
intmax_t	A signed integer type capable of representing any value of any signed integer type.	stdint.h
intptr_t (long integer or __int64, depending on the target platform)	Stores a pointer (or HANDLE) on both Win32 and Win64 platforms.	STDDEF.H and other include files
jmp_buf array	Used by setjmp and longjmp to save and restore program environment.	SETJMP.H
lconv structure	Contains formatting rules for numeric values in different countries/regions. Used by localeconv.	LOCALE.H
_LDOUBLE, _LONGDOUBLE, _LDBL12 (long double or an unsigned char array)	Use to represent a long double value.	STDLIB.H
_locale_t structure	Stores current locale values; used in all locale specific C run-time libraries.	CRTDEFS.H
mbstate_t	Tracks the state of a multibyte character conversion.	WCHAR.H
off_t, _off_t long integer	Represents file-offset value.	WCHAR.H, SYS\TYPES.H
_onexit_t, _onexit_m_t pointer	Returned by _onexit, _onexit_m.	STDLIB.H
_PNH pointer to function	Type of argument to _set_new_handler.	NEW.H
ptrdiff_t (long integer or __int64, depending on the target platform)	Result of subtraction of two pointers.	CRTDEFS.H
_purecall_handler, _purecall_handler_m	A type definition for a call-back function that is called when a pure virtual function is called. Used by _get_purecall_handler, _set_purecall_handler. A _purecall_handler function should have a void return type.	STDLIB.H
_RTC_error_fn type definition	A type definition for a function that will handle run-time error checks. Used in _RTC_SetErrorFunc.	RTCAPI.H
_RTC_error_fnW type definition	A type definition for a function that will handle run-time error checks. Used in _RTC_SetErrorFuncW.	RTCAPI.H
_RTC_ErrorNumber enumeration	Defines error conditions for _RTC_GetErrDesc and _RTC_SetErrorType.	RTCAPI.H
_se_translator_function	A type definition for a call-back function that translates an exception. The first parameter is the exception code and the second parameter is the exception record. Used by _set_se_translator.	EH.H
sig_atomic_t integer	Type of object that can be modified as atomic entity, even in presence of asynchronous interrupts; used with signal.	SIGNAL.H
size_t (unsigned __int64 or unsigned integer, depending on the target platform)	Result of sizeof operator.	CRTDEFS.H and other include files
_stat structure	Contains file-status information returned by _stat and _fstat.	SYS\STAT.H
__stat64 structure	Contains file-status information returned by _fstat64 and _stat64, and _wstat64.	SYS\STAT.H
_stati64 structure	Contains file-status information returned by _fstati64, _stati64, and _wstati64.	SYS\STAT.H
terminate_function type definition	A type definition for a call-back function that is called when terminate is called. Used by set_terminate.	EH.H
time_t (__int64 or long integer)	Represents time values in mktime, time, ctime, _ctime32, _ctime64, _wctime, _wctime32, _wctime64, ctime_s, _ctime32_s, _ctime64_s, _wctime_s, _wctime32_s, _wctime64_s, ctime, _ctime32, _ctime64, _wctime, _wctime32, _wctime64 and gmtime, _gmtime32, _gmtime64. The number of seconds since January 1, 1970, 0:00 UTC. If _USE_32BIT_TIME_T is defined, time_t is a long integer. If not defined, it's a 64-bit integer.	TIME.H, SYS\STAT.H, SYS\TIMEB.H
__time32_t (long integer)	Represents time values in mktime, _mktime32, _mktime64, ctime, _ctime32, _ctime64, _wctime, _wctime32, _wctime64, ctime_s, _ctime32_s, _ctime64_s, _wctime_s, _wctime32_s, _wctime64_s, gmtime, _gmtime32, _gmtime64 and localtime, _localtime32, _localtime64.	CRTDEFS.H, SYS\STAT.H, SYS\TIMEB.H
__time64_t (__int64)	Represents time values in mktime, _mktime32, _mktime64, _ctime64, _wctime64, ctime_s, _ctime32_s, _ctime64_s, _wctime_s, _wctime32_s, _wctime64_s, _gmtime64, _localtime64 and _time64.	TIME.H, SYS\STAT.H, SYS\TIMEB.H
_timeb structure	The _ftime and _ftime_s, _ftime32_s, _ftime64_s functions use it to store current system time.	SYS\TIMEB.H
__timeb32 structure	The _ftime, _ftime32, _ftime64 and _ftime_s, _ftime32_s, _ftime64_s functions use it to store current system time.	SYS\TIMEB.H
__timeb64 structure	The _ftime64 and _ftime_s, _ftime32_s, _ftime64_s functions use it to store current system time.	SYS\TIMEB.H
tm structure	The asctime, _wasctime, asctime_s, _wasctime_s, gmtime, _gmtime32, _gmtime64, gmtime_s, _gmtime32_s, _gmtime64_s, localtime, _localtime32, _localtime64, localtime_s, _localtime32_s, _localtime64_s, mktime, _mktime32, _mktime64 and strftime, wcsftime, _strftime_l, _wcsftime_l functions use it to store and retrieve time information.	TIME.H
uintmax_t	An unsigned integer type capable of representing any value of any unsigned integer type.	stdint.h
uintptr_t (long integer or __int64, depending on the target platform)	An unsigned integer or unsigned __int64 version of intptr_t.	STDDEF.H and other include files
unexpected_function	A type definition for a call-back function that is called when unexpected is called. Used by set_unexpected.	EH.H
_utimbuf structure	Stores file access and modification times used by _utime, _wutime and _futime, _futime32, _futime64 to change file-modification dates.	SYS\UTIME.H
_utimbuf32 structure	Stores file access and modification times used by _utime, _utime32, _utime64, _wutime, _wutime32, _wutime64 and _futime, _futime32, _futime64 to change file-modification dates.	SYS\UTIME.H
__utimbuf64 structure	The _utime64, _wutime64 and _futime64 functions use it to store the current time.	SYS\UTIME.H
va_list structure	Used to hold information needed by va_arg and va_end macros. Called function declares variable of type va_list that can be passed as argument to another function.	STDARG.H, CRTDEFS.H
wchar_t wide character	Useful for writing portable programs for international markets.	STDDEF.H, STDLIB.H, CRTDEFS.H, SYS\STAT.H
wctrans_t integer	Represents locale-specific character mappings.	WCTYPE.H
wctype_t integer	Can represent all characters of any language character set.	WCHAR.H, CRTDEFS.H
wint_t integer	Type of data object that can hold any wide character or wide end-of-file value.	WCHAR.H, CRTDEFS.H

See also

C runtime library reference