|ECVT(3)||Linux Programmer's Manual||ECVT(3)|
NAMEecvt, fcvt - convert a floating-point number to a string
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
- Since glibc 2.12:
(_XOPEN_SOURCE >= 500 ||
_XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED) &&
!(_POSIX_C_SOURCE >= 200112L || _XOPEN_SOURCE >= 600)
- Before glibc 2.12:
- _SVID_SOURCE || _XOPEN_SOURCE >= 500 || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
DESCRIPTIONThe 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 VALUEBoth 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().
Multithreading (see pthreads(7))The ecvt() and fcvt() functions are not thread-safe.
CONFORMING TOSVr2; 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).
NOTESLinux libc4 and libc5 specified the type of ndigits as size_t. Not all locales use a point as the radix character ("decimal point").
SEE ALSOecvt_r(3), gcvt(3), qecvt(3), setlocale(3), sprintf(3)
COLOPHONThis page is part of release 3.53 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.