man3/gcvt.3

   1 .\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
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  25 .\" References consulted:
  26 .\"     Linux libc source code
  27 .\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
  28 .\"     386BSD man pages
  29 .\" Modified Sat Jul 24 19:32:25 1993 by Rik Faith (faith@cs.unc.edu)
  30 .TH GCVT 3 2015-03-29 "" "Linux Programmer's Manual"
  31 .SH NAME
  32 gcvt \- convert a floating-point number to a string
  33 .SH SYNOPSIS
  34 .nf
  35 .B #include <stdlib.h>
  36 .sp
  37 .BI "char *gcvt(double " number ", int " ndigit ", char *" buf );
  38 .fi
  39 .sp
  40 .in -4n
  41 Feature Test Macro Requirements for glibc (see
  42 .BR feature_test_macros (7)):
  43 .in
  44 .sp
  45 .BR gcvt ():
  46 .ad l
  47 .PD 0
  48 .RS 4
  49 .TP 4
  50 Since glibc 2.12:
  51 .nf
  52 _SVID_SOURCE ||
  53     (_XOPEN_SOURCE\ >=\ 500 ||
  54         _XOPEN_SOURCE\ &&\ _XOPEN_SOURCE_EXTENDED) &&
  55     !(_POSIX_C_SOURCE\ >=\ 200112L || _XOPEN_SOURCE\ >=\ 600)
  56 .fi
  57 .TP 4
  58 Before glibc 2.12:
  59 _SVID_SOURCE || _XOPEN_SOURCE\ >=\ 500 ||
  60 _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
  61 .RE
  62 .PD
  63 .ad b
  64 .SH DESCRIPTION
  65 The
  66 .BR gcvt ()
  67 function converts \fInumber\fP to a minimal length null-terminated
  68 ASCII string and stores the result in \fIbuf\fP.
  69 It produces \fIndigit\fP significant digits in either
  70 .BR printf (3)
  71 F format or E format.
  72 .SH RETURN VALUE
  73 The
  74 .BR gcvt ()
  75 function returns the address of the string pointed to
  76 by \fIbuf\fP.
  77 .SH ATTRIBUTES
  78 For an explanation of the terms used in this section, see
  79 .BR attributes (7).
  80 .TS
  81 allbox;
  82 lb lb lb
  83 l l l.
  84 Interface       Attribute       Value
  85 T{
  86 .BR gcvt ()
  87 T}      Thread safety   MT-Safe
  88 .TE
  89
  90 .SH CONFORMING TO
  91 Marked as LEGACY in POSIX.1-2001.
  92 POSIX.1-2008 removes the specification of
  93 .BR gcvt (),
  94 recommending the use of
  95 .BR sprintf (3)
  96 instead (though
  97 .BR snprintf (3)
  98 may be preferable).
  99 .SH SEE ALSO
 100 .BR ecvt (3),
 101 .BR fcvt (3),
 102 .BR sprintf (3)