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1449. Incomplete specification of header <cinttypes>

Section: 31.8.3 [istringstream] Status: C++11 Submitter: Canada Opened: 2010-08-25 Last modified: 2016-01-28

Priority: Not Prioritized

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Discussion:

Addresses CA-4

Subclause 27.9.2 [c.files] specifies that <cinttypes> has declarations for abs() and div(); however, the signatures are not present in this subclause. The signatures proposed under TR1 ([tr.c99.inttypes]) are not present in FCD (unless if intmax_t happened to be long long). It is unclear as to which, if any of the abs() and div() functions in [c.math] are meant to be declared by <cinttypes>. This subclause mentions imaxabs() and imaxdiv(). These functions, among other things, are not specified in FCD to be the functions from Subclause 7.8 of the C Standard. Finally, <cinttypes> is not specified in FCD to include <cstdint> (whereas <inttypes.h> includes <stdint.h> in C).

[ Post-Rapperswil, Daniel provides wording ]

Subclause [c.files] specifies that <cinttypes> has declarations for abs() and div(); however, the signatures are not present in this subclause. The signatures proposed under TR1 ([tr.c99.inttypes]) are not present in FCD (unless if intmax_t happened to be long long). It is unclear as to which, if any of the abs() and div() functions in [c.math] are meant to be declared by <cinttypes>. This subclause mentions imaxabs() and imaxdiv(). These functions, among other things, are not specified in FCD to be the functions from subclause 7.8 of the C Standard. Finally, <cinttypes> is not specified in FCD to include <cstdint> (whereas <inttypes.h> includes <stdint.h> in C).

Moved to Tentatively Ready with proposed wording after 5 positive votes on c++std-lib.

[ Adopted at 2010-11 Batavia ]

Proposed resolution:

The wording refers to N3126.

1. Add the following series of new paragraphs following [c.files] p.1:

   Table 132 describes header <cinttypes>. [Note: The macros defined by <cinttypes> are provided unconditionally. In particular, the symbol __STDC_FORMAT_MACROS, mentioned in footnote 182 of the C standard, plays no role in C++. — end note ]

   2 - The contents of header <cinttypes> are the same as the Standard C library header <inttypes.h>, with the following changes:

   3 - The header <cinttypes> includes the header <cstdint> instead of <stdint.h>.

   4 - If and only if the type intmax_t designates an extended integer type ([basic.fundamental]), the following function signatures are added:

   intmax_t abs(intmax_t);
   imaxdiv_t div(intmax_t, intmax_t);
   

   which shall have the same semantics as the function signatures intmax_t imaxabs(intmax_t) and imaxdiv_t imaxdiv(intmax_t, intmax_t), respectively.