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PROLOG | NAME | SYNOPSIS | DESCRIPTION | EXAMPLES | APPLICATION USAGE | RATIONALE | FUTURE DIRECTIONS | SEE ALSO | COPYRIGHT |
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inttypes.h(0P) POSIX Programmer's Manual inttypes.h(0P)
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.
inttypes.h — fixed size integer types
#include <inttypes.h>
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.1‐2017, 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 int_fast32_t.
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.
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.
#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 platforms.
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> header.
stddef.h(0p)
The System Interfaces volume of POSIX.1‐2017, Section 2.2, The
Compilation Environment, imaxabs(3p), imaxdiv(3p), strtoimax(3p),
wcstoimax(3p)
Portions of this text are reprinted and reproduced in electronic
form from IEEE Std 1003.1-2017, Standard for Information
Technology -- Portable Operating System Interface (POSIX), The
Open Group Base Specifications Issue 7, 2018 Edition, Copyright
(C) 2018 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 original Standard can be obtained online at
http://www.opengroup.org/unix/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
https://www.kernel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group 2017 inttypes.h(0P)
Pages that refer to this page: arpa_inet.h(0p), netdb.h(0p), netinet_in.h(0p), stdint.h(0p), fprintf(3p), fscanf(3p), fwprintf(3p), fwscanf(3p), htonl(3p), imaxabs(3p), imaxdiv(3p), strtoimax(3p), wcstoimax(3p)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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