The Open Group Base Specifications Issue 6
IEEE Std 1003.1-2001
Copyright © 2001 The IEEE and The Open Group, All Rights reserved.

NAME

inttypes.h - fixed size integer types

SYNOPSIS

#include <inttypes.h>

DESCRIPTION

[CX] [Option Start] 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. [Option End]

The <inttypes.h> header shall include the <stdint.h> header.

The <inttypes.h> header shall include a definition of at least the following type:

imaxdiv_t
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 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);

EXAMPLES

#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 following sections are informative.

APPLICATION USAGE

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 platforms.

RATIONALE

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.

FUTURE DIRECTIONS

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.

SEE ALSO

The System Interfaces volume of IEEE Std 1003.1-2001, imaxdiv()

CHANGE HISTORY

First released in Issue 5.

Issue 6

The Open Group Base Resolution bwg97-006 is applied.

This reference page is updated to align with the ISO/IEC 9899:1999 standard.

End of informative text.


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