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Diffstat (limited to 'manual')
| -rw-r--r-- | manual/arith.texi | 41 |
1 files changed, 41 insertions, 0 deletions
diff --git a/manual/arith.texi b/manual/arith.texi index e53988a083..eaaf2b7127 100644 --- a/manual/arith.texi +++ b/manual/arith.texi @@ -20,6 +20,7 @@ These functions are declared in the header files @file{math.h} and * Complex Numbers:: The types. Writing complex constants. * Operations on Complex:: Projection, conjugation, decomposition. * Parsing of Numbers:: Converting strings to numbers. +* Printing of Floats:: Converting floating-point numbers to strings. * System V Number Conversion:: An archaic way to convert numbers to strings. @end menu @@ -2806,6 +2807,46 @@ which take an additional argument, the locale to use in conversion. See also @ref{Parsing of Integers}. +@node Printing of Floats +@section Printing of Floats + +@pindex stdlib.h +The @samp{strfrom} functions are declared in @file{stdlib.h}. + +@comment stdlib.h +@comment ISO/IEC TS 18661-1 +@deftypefun int strfromd (char *restrict @var{string}, size_t @var{size}, const char *restrict @var{format}, double @var{value}) +@deftypefunx int strfromf (char *restrict @var{string}, size_t @var{size}, const char *restrict @var{format}, float @var{value}) +@deftypefunx int strfroml (char *restrict @var{string}, size_t @var{size}, const char *restrict @var{format}, long double @var{value}) +@safety{@prelim{}@mtsafe{@mtslocale{}}@asunsafe{@ascuheap{}}@acunsafe{@acsmem{}}} +@comment these functions depend on __printf_fp and __printf_fphex, which are +@comment AS-unsafe (ascuheap) and AC-unsafe (acsmem). +The functions @code{strfromd} (``string-from-double''), @code{strfromf} +(``string-from-float''), and @code{strfroml} (``string-from-long-double'') +convert the floating-point number @var{value} to a string of characters and +stores them into the area pointed to by @var{string}. The conversion +writes at most @var{size} characters and respects the format specified by +@var{format}. + +The format string must start with the character @samp{%}. An optional +precision follows, which starts with a period, @samp{.}, and may be +followed by a decimal integer, representing the precision. If a decimal +integer is not specified after the period, the precision is taken to be +zero. The character @samp{*} is not allowed. Finally, the format string +ends with one of the following conversion specifiers: @samp{a}, @samp{A}, +@samp{e}, @samp{E}, @samp{f}, @samp{F}, @samp{g} or @samp{G} (@pxref{Table +of Output Conversions}). Invalid format strings result in undefined +behavior. + +These functions return the number of characters that would have been +written to @var{string} had @var{size} been sufficiently large, not +counting the terminating null character. Thus, the null-terminated output +has been completely written if and only if the returned value is less than +@var{size}. + +These functions were introduced by ISO/IEC TS 18661-1. +@end deftypefun + @node System V Number Conversion @section Old-fashioned System V number-to-string functions |