man3/gcvt.3

   1 '\" t
   2 .\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
   3 .\"
   4 .\" SPDX-License-Identifier: Linux-man-pages-copyleft
   5 .\"
   6 .\" References consulted:
   7 .\"     Linux libc source code
   8 .\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
   9 .\"     386BSD man pages
  10 .\" Modified Sat Jul 24 19:32:25 1993 by Rik Faith (faith@cs.unc.edu)
  11 .TH gcvt 3 (date) "Linux man-pages (unreleased)"
  12 .SH NAME
  13 gcvt \- convert a floating-point number to a string
  14 .SH LIBRARY
  15 Standard C library
  16 .RI ( libc ", " \-lc )
  17 .SH SYNOPSIS
  18 .nf
  19 .B #include <stdlib.h>
  20 .PP
  21 .BI "char *gcvt(double " number ", int " ndigit ", char *" buf );
  22 .fi
  23 .PP
  24 .RS -4
  25 Feature Test Macro Requirements for glibc (see
  26 .BR feature_test_macros (7)):
  27 .RE
  28 .PP
  29 .BR gcvt ():
  30 .nf
  31     Since glibc 2.17
  32         (_XOPEN_SOURCE >= 500 && ! (_POSIX_C_SOURCE >= 200809L))
  33             || /* glibc >= 2.20 */ _DEFAULT_SOURCE
  34             || /* glibc <= 2.19 */ _SVID_SOURCE
  35     glibc 2.12 to glibc 2.16:
  36         (_XOPEN_SOURCE >= 500 && ! (_POSIX_C_SOURCE >= 200112L))
  37             || _SVID_SOURCE
  38     Before glibc 2.12:
  39         _SVID_SOURCE || _XOPEN_SOURCE >= 500
  40 .\"        || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
  41 .fi
  42 .SH DESCRIPTION
  43 The
  44 .BR gcvt ()
  45 function converts \fInumber\fP to a minimal length null-terminated
  46 ASCII string and stores the result in \fIbuf\fP.
  47 It produces \fIndigit\fP significant digits in either
  48 .BR printf (3)
  49 F format or E format.
  50 .SH RETURN VALUE
  51 The
  52 .BR gcvt ()
  53 function returns
  54 \fIbuf\fP.
  55 .SH ATTRIBUTES
  56 For an explanation of the terms used in this section, see
  57 .BR attributes (7).
  58 .TS
  59 allbox;
  60 lbx lb lb
  61 l l l.
  62 Interface       Attribute       Value
  63 T{
  64 .na
  65 .nh
  66 .BR gcvt ()
  67 T}      Thread safety   MT-Safe
  68 .TE
  69 .sp 1
  70 .SH STANDARDS
  71 None.
  72 .SH HISTORY
  73 Marked as LEGACY in POSIX.1-2001.
  74 POSIX.1-2008 removed it,
  75 recommending the use of
  76 .BR sprintf (3)
  77 instead (though
  78 .BR snprintf (3)
  79 may be preferable).
  80 .SH SEE ALSO
  81 .BR ecvt (3),
  82 .BR fcvt (3),
  83 .BR sprintf (3)