Manpages - ecvt.3

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

  #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

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).

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)

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