This manual page is part of the POSIX Programmer's Manual. The Linux
implementation of this interface may differ (consult the
corresponding Linux manual page for details of Linux behavior), or
the interface may not be implemented on Linux.
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 POSIX.1‐2008, Section2.2, 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 define at least the following types:
imaxdiv_t Structure type that is the type of the value returned by
the imaxdiv() function.
wchar_t As described in <stddef.h>.
The <inttypes.h> header shall define the following macros. Each
expands to a character string literal containing 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 corresponding integer type. These macros have the
general form of PRI (character string literals for the fprintf() and
fwprintf() family of functions) or SCN (character string literals for
the fscanf() and fwscanf() family of functions), followed by the
conversion specifier, 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, PRIdFAST32 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
The following shall be declared as functions and may also be defined
as macros. Function prototypes shall be provided.
intmax_t imaxabs(intmax_t);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);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, through 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 requirement 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.
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2013 Edition, Standard for Information
Technology -- Portable Operating System Interface (POSIX), The Open
Group Base Specifications Issue 7, Copyright (C) 2013 by the
Institute of Electrical and Electronics Engineers, Inc and The Open
Group. (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1
applied.) 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 original
Standard can be obtained online at http://www.unix.org/online.html .
Any typographical or formatting errors that appear in this page are
most likely to have been introduced during the conversion of the
source files to man page format. To report such errors, see
IEEE/The Open Group 2013 inttypes.h(0P)