ecvt(3) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ATTRIBUTES | CONFORMING TO | NOTES | SEE ALSO | COLOPHON

ECVT(3)                 Linux Programmer's Manual                ECVT(3)

NAME         top

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

SYNOPSIS         top

       #include <stdlib.h>

       char *ecvt(double number, int ndigits, int *restrict decpt,
                  int *restrict sign);
       char *fcvt(double number, int ndigits, int *restrict decpt,
                  int *restrict sign);

   Feature Test Macro Requirements for glibc (see
   feature_test_macros(7)):

       ecvt(), fcvt():
           Since glibc 2.17
               (_XOPEN_SOURCE >= 500 && ! (_POSIX_C_SOURCE >= 200809L))
                   || /* Glibc >= 2.20 */ _DEFAULT_SOURCE
                   || /* Glibc <= 2.19 */ _SVID_SOURCE
           Glibc versions 2.12 to 2.16:
               (_XOPEN_SOURCE >= 500 && ! (_POSIX_C_SOURCE >= 200112L))
                   || _SVID_SOURCE
           Before glibc 2.12:
               _SVID_SOURCE || _XOPEN_SOURCE >= 500

DESCRIPTION         top

       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         top

       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         top

       For an explanation of the terms used in this section, see
       attributes(7).

       ┌──────────────────────────┬───────────────┬─────────────────────┐
       │Interface                 Attribute     Value               │
       ├──────────────────────────┼───────────────┼─────────────────────┤
       │ecvt()                    │ Thread safety │ MT-Unsafe race:ecvt │
       ├──────────────────────────┼───────────────┼─────────────────────┤
       │fcvt()                    │ Thread safety │ MT-Unsafe race:fcvt │
       └──────────────────────────┴───────────────┴─────────────────────┘

CONFORMING TO         top

       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         top

       Not all locales use a point as the radix character ("decimal
       point").

SEE ALSO         top

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

COLOPHON         top

       This page is part of release 5.13 of the Linux man-pages project.
       A description of the project, information about reporting bugs,
       and the latest version of this page, can be found at
       https://www.kernel.org/doc/man-pages/.

                               2021-03-22                        ECVT(3)

Pages that refer to this page: ecvt_r(3)gcvt(3)qecvt(3)