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NAME |LIBRARY |SYNOPSIS |DESCRIPTION |RETURN VALUE |ATTRIBUTES |STANDARDS |HISTORY |NOTES |SEE ALSO |COLOPHON | |
ecvt(3) Library Functions Manualecvt(3)ecvt, fcvt - convert a floating-point number to a string
Standard C library (libc,-lc)
#include <stdlib.h>[[deprecated]] char *ecvt(doublenumber, intndigits,int *restrictdecpt, int *restrictsign);[[deprecated]] char *fcvt(doublenumber, intndigits,int *restrictdecpt, int *restrictsign); Feature Test Macro Requirements for glibc (seefeature_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
Theecvt() function convertsnumber to a null-terminated string ofndigits digits (wherendigits is reduced to a system-specific limit determined by the precision of adouble), and returns a pointer to the string. The high-order digit is nonzero, unlessnumber 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 ofnumber is negative,*sign is set to a nonzero value, otherwise it is set to 0. Ifnumber is zero, it is unspecified whether*decpt is 0 or 1. Thefcvt() function is identical toecvt(), except thatndigits specifies the number of digits after the decimal point.
Both theecvt() andfcvt() functions return a pointer to a static string containing the ASCII representation ofnumber. The static string is overwritten by each call toecvt() orfcvt().
For an explanation of the terms used in this section, seeattributes(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 ofecvt() andfcvt(), recommending the use ofsprintf(3) instead (thoughsnprintf(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 theman-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 isnot part of the original manual page), send a mail to man-pages@man7.orgLinux man-pages 6.15 2025-05-17ecvt(3)Pages that refer to this page:ecvt_r(3), gcvt(3), qecvt(3)
HTML rendering created 2025-09-06 byMichael Kerrisk, author ofThe Linux Programming Interface. For details of in-depthLinux/UNIX system programming training courses that I teach, lookhere. Hosting byjambit GmbH. | |