man3/ecvt.3

   1 .\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
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  23 .\" References consulted:
  24 .\"     Linux libc source code
  25 .\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
  26 .\"     386BSD man pages
  27 .\" Modified Sat Jul 24 19:40:39 1993 by Rik Faith (faith@cs.unc.edu)
  28 .\" Modified Fri Jun 25 12:10:47 1999 by Andries Brouwer (aeb@cwi.nl)
  29 .\"
  30 .TH ECVT 3  1999-06-25 "" "Linux Programmer's Manual"
  31 .SH NAME
  32 ecvt, fcvt \- convert a floating-point number to a string
  33 .SH SYNOPSIS
  34 .B #include <stdlib.h>
  35 .sp
  36 .BI "char *ecvt(double " number ", int " ndigits ", int *" decpt ,
  37 .BI "int *" sign );
  38 .sp
  39 .BI "char *fcvt(double " number ", int " ndigits ", int *" decpt ,
  40 .BI "int *" sign );
  41 .SH DESCRIPTION
  42 The \fBecvt\fP() function converts \fInumber\fP to a null-terminated
  43 string of \fIndigits\fP digits (where \fIndigits\fP is reduced to an
  44 system-specific limit determined by the precision of a double),
  45 and returns a pointer to the string. The high-order digit is non-zero,
  46 unless
  47 .I number
  48 is zero. The low order digit is rounded.
  49 The string itself does not contain a decimal point; however,
  50 the position of the decimal point relative to the start of the string
  51 is stored in *\fIdecpt\fP. A negative value for *\fIdecpt\fP means that
  52 the decimal point is to the left of the start of the string.  If the sign of
  53 \fInumber\fP is negative, *\fIsign\fP is set to a non-zero value, otherwise
  54 it's set to 0. If
  55 .I number
  56 is zero, it is unspecified whether *\fIdecpt\fP is 0 or 1.
  57 .PP
  58 The \fBfcvt\fP() function is identical to \fBecvt\fP(), except that
  59 \fIndigits\fP specifies the number of digits after the decimal point.
  60 .SH "RETURN VALUE"
  61 Both the \fBecvt\fP() and \fBfcvt\fP() functions return a pointer to a
  62 static string containing the ASCII representation of \fInumber\fP.
  63 The static string is overwritten by each call to \fBecvt\fP() or
  64 \fBfcvt\fP().
  65 .SH NOTES
  66 These functions are obsolete. Instead,
  67 .IR sprintf ()
  68 is recommended.
  69 Linux libc4 and libc5 specified the type of
  70 .I ndigits
  71 as
  72 .BR size_t .
  73 Not all locales use a point as the radix character (`decimal point').
  74 .SH "CONFORMING TO"
  75 SysVR2, XPG2
  76 .SH "SEE ALSO"
  77 .BR ecvt_r (3),
  78 .BR gcvt (3),
  79 .BR qecvt (3),
  80 .BR setlocale (3),
  81 .BR sprintf (3)