<inttypes.h>(P) POSIX Programmer's Manual <inttypes.h>(P)
inttypes.h - fixed size integer types
Some of the functionality described on this reference page extends the ISO C standard.
Applications shall define the appropriate feature test macro (see the System Interfaces
volume of IEEE Std 1003.1-2001, Section 2.2, The Compilation Environment) to enable the
visibility of these symbols in this header.
The <inttypes.h> header shall include the <stdint.h> header.
The <inttypes.h> header shall include a definition of at least the following type:
Structure type that is the type of the value returned by the imaxdiv() function.
The following macros shall be defined. Each expands to a character string literal contain-
ing a conversion specifier, possibly modified by a length modifier, suitable for use
within the format argument of a formatted input/output function when converting the corre-
sponding integer type. These macros have the general form of PRI (character string liter-
als for the fprintf() and fwprintf() family of functions) or SCN (character string liter-
als for the fscanf() and fwscanf() family of functions), followed by the conversion speci-
fier, followed by a name corresponding to a similar type name in <stdint.h>. In these
names, N represents the width of the type as described in <stdint.h>. For example, PRId-
FAST32 can be used in a format string to print the value of an integer of type
The fprintf() macros for signed integers are:
PRIdN PRIdLEASTN PRIdFASTN PRIdMAX PRIdPTR
PRIiN PRIiLEASTN PRIiFASTN PRIiMAX PRIiPTR
The fprintf() macros for unsigned integers are:
PRIoN PRIoLEASTN PRIoFASTN PRIoMAX PRIoPTR
PRIuN PRIuLEASTN PRIuFASTN PRIuMAX PRIuPTR
PRIxN PRIxLEASTN PRIxFASTN PRIxMAX PRIxPTR
PRIXN PRIXLEASTN PRIXFASTN PRIXMAX PRIXPTR
The fscanf() macros for signed integers are:
SCNdN SCNdLEASTN SCNdFASTN SCNdMAX SCNdPTR
SCNiN SCNiLEASTN SCNiFASTN SCNiMAX SCNiPTR
The fscanf() macros for unsigned integers are:
SCNoN SCNoLEASTN SCNoFASTN SCNoMAX SCNoPTR
SCNuN SCNuLEASTN SCNuFASTN SCNuMAX SCNuPTR
SCNxN SCNxLEASTN SCNxFASTN SCNxMAX SCNxPTR
For each type that the implementation provides in <stdint.h>, the corresponding fprintf()
and fwprintf() macros shall be defined and the corresponding fscanf() and fwscanf() macros
shall be defined unless the implementation does not have a suitable modifier for the type.
The following shall be declared as functions and may also be defined as macros. Function
prototypes shall be provided.
imaxdiv_t imaxdiv(intmax_t, intmax_t);
intmax_t strtoimax(const char *restrict, char **restrict, int);
uintmax_t strtoumax(const char *restrict, char **restrict, int);
intmax_t wcstoimax(const wchar_t *restrict, wchar_t **restrict, int);
uintmax_t wcstoumax(const wchar_t *restrict, wchar_t **restrict, int);
uintmax_t i = UINTMAX_MAX; // This type always exists.
wprintf(L"The largest integer value is %020"
PRIxMAX "\n", i);
The following sections are informative.
The purpose of <inttypes.h> is to provide a set of integer types whose definitions are
consistent across machines and independent of operating systems and other implementation
idiosyncrasies. It defines, via typedef, integer types of various sizes. Implementations
are free to typedef them as ISO C standard integer types or extensions that they support.
Consistent use of this header will greatly increase the portability of applications across
The ISO/IEC 9899:1990 standard specified that the language should support four signed and
unsigned integer data types- char, short, int, and long- but placed very little require-
ment on their size other than that int and short be at least 16 bits and long be at least
as long as int and not smaller than 32 bits. For 16-bit systems, most implementations
assigned 8, 16, 16, and 32 bits to char, short, int, and long, respectively. For 32-bit
systems, the common practice has been to assign 8, 16, 32, and 32 bits to these types.
This difference in int size can create some problems for users who migrate from one system
to another which assigns different sizes to integer types, because the ISO C standard
integer promotion rule can produce silent changes unexpectedly. The need for defining an
extended integer type increased with the introduction of 64-bit systems.
Macro names beginning with PRI or SCN followed by any lowercase letter or 'X' may be added
to the macros defined in the <inttypes.h> header.
The System Interfaces volume of IEEE Std 1003.1-2001, imaxdiv()
Portions of this text are reprinted and reproduced in electronic form from IEEE Std
1003.1, 2003 Edition, Standard for Information Technology -- Portable Operating System
Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 by
the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the
event of any discrepancy between this version and the original IEEE and The Open Group
Standard, the original IEEE and The Open Group Standard is the referee document. The orig-
inal Standard can be obtained online at http://www.opengroup.org/unix/online.html .
IEEE/The Open Group 2003 <inttypes.h>(P)