ecvt(3)			    Library Functions Manual			 ecvt(3)

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

LIBRARY
     Standard C library (libc, -lc)

SYNOPSIS
     #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

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  over-
     written by each call to ecvt() or fcvt().

ATTRIBUTES
     For  an  explanation  of the terms used in this section, see attributes(7).
     allbox; lbx lb lb l l l.  Interface Attribute Value T{ ecvt() T}	Thread
     safety  MT-Unsafe race:ecvt T{ fcvt() T}	Thread safety  MT-Unsafe
     race:fcvt

STANDARDS
     None.

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

NOTES
     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)

Linux man-pages 6.18		   2026-02-08				 ecvt(3)