fcvt(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 \nnumber\n, int \nndigits\n,\n
\n                          int *restrict \ndecpt\n, int *restrict \nsign\n);\n
\n[[deprecated]] char *fcvt(double \nnumber\n, int \nndigits\n,\n
\n                          int *restrict \ndecpt\n, int *restrict \nsign\n);

ecvt(), fcvt():

\n
    Since glibc 2.17
\n
        (_XOPEN_SOURCE >= 500 && ! (_POSIX_C_SOURCE >= 200809L))
\n
            || /* glibc >= 2.20 */ _DEFAULT_SOURCE
\n
            || /* glibc <= 2.19 */ _SVID_SOURCE
\n
    glibc 2.12 to glibc 2.16:
\n
        (_XOPEN_SOURCE >= 500 && ! (_POSIX_C_SOURCE >= 200112L))
\n
            || _SVID_SOURCE
\n
    Before glibc 2.12:
\n
        _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 overwritten by each call to ecvt() or fcvt().

ATTRIBUTES#

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

STANDARDS#

None.

HISTORY#

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#

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)