ecvt, fcvt - convert a floating-point number to a string
#include <stdlib.h>
char *ecvt(double number, int ndigits, int
*decpt, int *sign);
char *fcvt(double number, int ndigits, int
*decpt, int *sign);
Feature Test Macro Requirements for glibc (see
feature_test_macros(7)):
ecvt(),
fcvt():
- Since glibc 2.12:
-
(_XOPEN_SOURCE >= 500) ! (_POSIX_C_SOURCE >= 200112L)
|| /* Glibc since 2.19: */ _DEFAULT_SOURCE
|| /* Glibc versions <= 2.19: */ _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 |
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)