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ECVT(3P)                   POSIX Programmer's Manual                  ECVT(3P)

PROLOG
       This  manual  page is part of the POSIX Programmer's Manual.  The Linux
       implementation of this interface may differ (consult the  corresponding
       Linux  manual page for details of Linux behavior), or the interface may
       not be implemented on Linux.
NAME
       ecvt, fcvt, gcvt - convert a floating-point number to a string (LEGACY)
SYNOPSIS
       #include <stdlib.h>
       char *ecvt(double value, int ndigit, int *restrict decpt,
              int *restrict sign);
       char *fcvt(double value, int ndigit, int *restrict decpt,
              int *restrict sign);
       char *gcvt(double value, int ndigit, char *buf);

DESCRIPTION
       The ecvt(), fcvt(), and gcvt() functions shall  convert  floating-point
       numbers to null-terminated strings.
       The  ecvt() function shall convert value to a null-terminated string of
       ndigit digits (where ndigit is reduced to an unspecified  limit  deter-
       mined by the precision of a double) and return a pointer to the string.
       The high-order digit shall be non-zero, unless the value is 0. The low-
       order  digit  shall be rounded in an implementation-defined manner. The
       position of the radix character relative to the beginning of the string
       shall  be  stored in the integer pointed to by decpt (negative means to
       the left of the returned digits). If value is zero, it  is  unspecified
       whether  the  integer  pointed  to  by decpt would be 0 or 1. The radix
       character shall not be included in the returned string. If the sign  of
       the  result  is  negative, the integer pointed to by sign shall be non-
       zero; otherwise, it shall be 0.
       If the converted value is out of range or  is  not  representable,  the
       contents of the returned string are unspecified.
       The  fcvt()  function shall be equivalent to ecvt(), except that ndigit
       specifies the number of digits desired after the radix  character.  The
       total number of digits in the result string is restricted to an unspec-
       ified limit as determined by the precision of a double.
       The gcvt() function shall convert value  to  a  null-terminated  string
       (similar to that of the %g conversion specification format of printf())
       in the array pointed to by buf and shall return buf. It  shall  produce
       ndigit  significant  digits (limited to an unspecified value determined
       by the precision of a double) in the %f conversion specification format
       of  printf()  if possible, or the %e conversion specification format of
       printf()  (scientific  notation)  otherwise.  A  minus  sign  shall  be
       included  in the returned string if value is less than 0. A radix char-
       acter shall be included in the returned string if value is not a  whole
       number.   Trailing zeros shall be suppressed where value is not a whole
       number. The radix character is determined by  the  current  locale.  If
       setlocale()  has  not  been  called  successfully,  the default locale,
       POSIX, is used. The default locale specifies a period ( '.'  )  as  the
       radix  character.   The LC_NUMERIC category determines the value of the
       radix character within the current locale.
       These functions need not be reentrant. A function that is not  required
       to be reentrant is not required to be thread-safe.
RETURN VALUE
       The ecvt() and fcvt() functions shall return a pointer to a null-termi-
       nated string of digits.
       The gcvt() function shall return buf.
       The return values from ecvt() and fcvt() may point to static data which
       may be overwritten by subsequent calls to these functions.
ERRORS
       No errors are defined.
       The following sections are informative.
EXAMPLES
       None.
APPLICATION USAGE
       The sprintf() function is preferred over this function.
RATIONALE
       None.
FUTURE DIRECTIONS
       These functions may be withdrawn in a future version.
SEE ALSO
       printf(),    setlocale(),    the    Base    Definitions    volume    of
       IEEE Std 1003.1-2001, <stdlib.h>
COPYRIGHT
       Portions of this text are reprinted and reproduced in  electronic  form
       from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
       -- Portable Operating System Interface (POSIX),  The  Open  Group  Base
       Specifications  Issue  6,  Copyright  (C) 2001-2003 by the Institute of
       Electrical and Electronics Engineers, Inc and The Open  Group.  In  the
       event of any discrepancy between this version and the original IEEE and
       The Open Group Standard, the original IEEE and The Open Group  Standard
       is  the  referee document. The original Standard can be obtained online
       at http://www.opengroup.org/unix/online.html .

IEEE/The Open Group                  2003                             ECVT(3P)