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NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUE | ATTRIBUTES | STANDARDS | HISTORY | NOTES | SEE ALSO | COLOPHON |
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ecvt(3) Library Functions Manual ecvt(3)
ecvt, fcvt - convert a floating-point number to a string
Standard C library (libc, -lc)
#include <stdlib.h>
[[deprecated]] char *ecvt(double number, int ndigits,
int *restrict decpt, int *restrict sign);
[[deprecated]] 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 2.12 to glibc 2.16:
(_XOPEN_SOURCE >= 500 && ! (_POSIX_C_SOURCE >= 200112L))
|| _SVID_SOURCE
Before glibc 2.12:
_SVID_SOURCE || _XOPEN_SOURCE >= 500
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.
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().
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 │
└──────────────────────────┴───────────────┴─────────────────────┘
None.
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).
Not all locales use a point as the radix character ("decimal
point").
ecvt_r(3), gcvt(3), qecvt(3), setlocale(3), sprintf(3)
This page is part of the man-pages (Linux kernel and C library
user-space interface documentation) project. Information about
the project can be found at
⟨https://www.kernel.org/doc/man-pages/⟩. If you have a bug report
for this manual page, see
⟨https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/CONTRIBUTING⟩.
This page was obtained from the tarball man-pages-6.15.tar.gz
fetched from
⟨https://mirrors.edge.kernel.org/pub/linux/docs/man-pages/⟩ on
2025-08-11. If you discover any rendering problems in this HTML
version of the page, or you believe there is a better or more up-
to-date source for the page, or you have corrections or
improvements to the information in this COLOPHON (which is not
part of the original manual page), send a mail to
man-pages@man7.org
Linux man-pages 6.15 2025-05-17 ecvt(3)
Pages that refer to this page: ecvt_r(3), gcvt(3), qecvt(3)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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