inttypes.h(0p) — Linux manual page


inttypes.h(0P)            POSIX Programmer's Manual           inttypes.h(0P)

PROLOG         top

       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.

NAME         top

       inttypes.h — fixed size integer types

SYNOPSIS         top

       #include <inttypes.h>

DESCRIPTION         top

       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, 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 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

       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.

EXAMPLES         top

       #include <inttypes.h>
       #include <wchar.h>
       int main(void)
           uintmax_t i = UINTMAX_MAX; // This type always exists.
           wprintf(L"The largest integer value is %020"
               PRIxMAX "\n", i);
           return 0;


       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

RATIONALE         top

       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.


       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>

SEE ALSO         top


       The System Interfaces volume of POSIX.1‐2008, Section 2.2, The
       Compilation Environment, imaxabs(3p), imaxdiv(3p), strtoimax(3p),

COPYRIGHT         top

       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 .

       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)

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