man3/gcvt.3

   1 .\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
   2 .\"
   3 .\" SPDX-License-Identifier: Linux-man-pages-copyleft
   4 .\"
   5 .\" References consulted:
   6 .\"     Linux libc source code
   7 .\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
   8 .\"     386BSD man pages
   9 .\" Modified Sat Jul 24 19:32:25 1993 by Rik Faith (faith@cs.unc.edu)
  10 .TH GCVT 3 2021-03-22 "Linux man-pages (unreleased)" "Linux Programmer's Manual"
  11 .SH NAME
  12 gcvt \- convert a floating-point number to a string
  13 .SH LIBRARY
  14 Standard C library
  15 .RI ( libc ", " \-lc )
  16 .SH SYNOPSIS
  17 .nf
  18 .B #include <stdlib.h>
  19 .PP
  20 .BI "char *gcvt(double " number ", int " ndigit ", char *" buf );
  21 .fi
  22 .PP
  23 .RS -4
  24 Feature Test Macro Requirements for glibc (see
  25 .BR feature_test_macros (7)):
  26 .RE
  27 .PP
  28 .BR gcvt ():
  29 .nf
  30     Since glibc 2.17
  31         (_XOPEN_SOURCE >= 500 && ! (_POSIX_C_SOURCE >= 200809L))
  32             || /* Glibc >= 2.20 */ _DEFAULT_SOURCE
  33             || /* Glibc <= 2.19 */ _SVID_SOURCE
  34     Glibc versions 2.12 to 2.16:
  35         (_XOPEN_SOURCE >= 500 && ! (_POSIX_C_SOURCE >= 200112L))
  36             || _SVID_SOURCE
  37     Before glibc 2.12:
  38         _SVID_SOURCE || _XOPEN_SOURCE >= 500
  39 .\"        || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
  40 .fi
  41 .SH DESCRIPTION
  42 The
  43 .BR gcvt ()
  44 function converts \fInumber\fP to a minimal length null-terminated
  45 ASCII string and stores the result in \fIbuf\fP.
  46 It produces \fIndigit\fP significant digits in either
  47 .BR printf (3)
  48 F format or E format.
  49 .SH RETURN VALUE
  50 The
  51 .BR gcvt ()
  52 function returns
  53 \fIbuf\fP.
  54 .SH ATTRIBUTES
  55 For an explanation of the terms used in this section, see
  56 .BR attributes (7).
  57 .ad l
  58 .nh
  59 .TS
  60 allbox;
  61 lbx lb lb
  62 l l l.
  63 Interface       Attribute       Value
  64 T{
  65 .BR gcvt ()
  66 T}      Thread safety   MT-Safe
  67 .TE
  68 .hy
  69 .ad
  70 .sp 1
  71 .SH STANDARDS
  72 Marked as LEGACY in POSIX.1-2001.
  73 POSIX.1-2008 removes the specification of
  74 .BR gcvt (),
  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)