преобразовать число с плавающей запятой в строку (convert a floating-point number to a string)
Имя (Name)
ecvt, fcvt - convert a floating-point number to a string
Синопсис (Synopsis)
#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
Описание (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.
Возвращаемое значение (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().
Атрибуты (Attributes)
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 │
└──────────────────────────┴───────────────┴─────────────────────┘
Стандарты (Conforming to)
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).
Примечание (Note)
Not all locales use a point as the radix character ("decimal
point").
Смотри также (See also)
ecvt_r(3), gcvt(3), qecvt(3), setlocale(3), sprintf(3)
