Linux manual pages Section 3: Subroutines  

Name

ecvt, fcvt — convert a floating-point number to a string

Synopsis

#include <stdlib.h>
char *ecvt( double number,
  int ndigits,
  int *decpt,
  int *sign);
 
char *fcvt( double number,
  int ndigits,
  int *decpt,
  int *sign);
 
[Note] Note
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
ecvt(), fcvt():
Since glibc 2.12:
_SVID_SOURCE || (_XOPEN_SOURCE >= 500 || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED) && !(_POSIX_C_SOURCE >= 200112L || _XOPEN_SOURCE >= 600)
Before glibc 2.12:
_SVID_SOURCE || _XOPEN_SOURCE >= 500 || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED

DESCRIPTION

The ecvt() function converts number to a null-terminated string of ndigits digits (where ndigits is reduced to a system-specific limit determined by the precision of a double), and returns a pointer to the string. The high-order digit is nonzero, unless number is zero. The low order digit is rounded. The string itself does not contain a decimal point; however, the position of the decimal point relative to the start of the string is stored in *decpt. A negative value for *decpt means that the decimal point is to the left of the start of the string. If the sign of number is negative, *sign is set to a nonzero value, otherwise it is set to 0. If number is zero, it is unspecified whether *decpt is 0 or 1.

The fcvt() function is identical to ecvt(), except that ndigits specifies the number of digits after the decimal point.

RETURN VALUE

Both the ecvt() and fcvt() functions return a pointer to a static string containing the ASCII representation of number. The static string is overwritten by each call to ecvt() or fcvt().

ATTRIBUTES

Multithreading (see pthreads(7))

The ecvt() and fcvt() functions are not thread-safe.

CONFORMING TO

SVr2; marked as LEGACY in POSIX.1-2001. POSIX.1-2008 removes the specifications of ecvt() and fcvt(), recommending the use of sprintf(3) instead (though snprintf(3) may be preferable).

NOTES

Linux libc4 and libc5 specified the type of ndigits as size_t. Not all locales use a point as the radix character ("decimal point").

SEE ALSO

ecvt_r(3), gcvt(3), qecvt(3), setlocale(3), sprintf(3)

COLOPHON

This page is part of release 3.52 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man−pages/.


  Copyright 1993 David Metcalfe (davidprism.demon.co.uk)

%%%LICENSE_START(VERBATIM)
Permission is granted to make and distribute verbatim copies of this
manual provided the copyright notice and this permission notice are
preserved on all copies.

Permission is granted to copy and distribute modified versions of this
manual under the conditions for verbatim copying, provided that the
entire resulting derived work is distributed under the terms of a
permission notice identical to this one.

Since the Linux kernel and libraries are constantly changing, this
manual page may be incorrect or out-of-date.  The author(s) assume no
responsibility for errors or omissions, or for damages resulting from
the use of the information contained herein.  The author(s) may not
have taken the same level of care in the production of this manual,
which is licensed free of charge, as they might when working
professionally.

Formatted or processed versions of this manual, if unaccompanied by
the source, must acknowledge the copyright and authors of this work.
%%%LICENSE_END

References consulted:
    Linux libc source code
    Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
    386BSD man pages
Modified Sat Jul 24 19:40:39 1993 by Rik Faith (faithcs.unc.edu)
Modified Fri Jun 25 12:10:47 1999 by Andries Brouwer (aebcwi.nl)