ecvt, fcvt, gcvt - convert floating-point number to string
char *ecvt(double value, int ndigit, int *decpt, int *sign);
char *fcvt(double value, int ndigit, int *decpt, int *sign);
char *gcvt(double value, int ndigit, char *buf);
The ecvt(), fcvt() and gcvt() functions convert floating-
point numbers to null-terminated strings.
The ecvt() function converts value to a null-terminated
string of ndigit digits (where ndigit is reduced to an
unspecified limit determined by the precision of a double)
and returns a pointer to the string. The high-order digit
is non-zero, unless the value is 0. The low-order digit is
The position of the radix character relative to the begin-
ning of the string is stored in the integer pointed to by
decpt (negative means to the left of the returned digits).
The radix character is not included in the returned string.
If the sign of the result is negative, the integer pointed
to by sign is non-zero, otherwise it is 0.
If the converted value is out of range or is not represent-
able, the contents of the returned string are unspecified.
The fcvt() function is identical to ecvt() except that ndi-
git specifies the number of digits desired after the radix
point. The total number of digits in the result string is
restricted to an unspecified limit as determined by the pre-
cision of a double.
The gcvt() function converts value to a null-terminated
string (similar to that of the %g format of printf(3C)) in
the array pointed to by buf and returns buf. It produces
ndigit significant digits (limited to an unspecified value
determined by the precision of a double) in %f if possible,
or %e (scientific notation) otherwise. A minus sign is
included in the returned string if value is less than 0. A
radix character is included in the returned string if value
is not a whole number. Trailing zeros are suppressed where
value is not a whole number. The radix character is deter-
mined by the current locale. If setlocale(3C) has not been
called successfully, the default locale, POSIX, is used.
The default locale specifies a period (.) as the radix char-
acter. The LC_NUMERIC category determines the value of the
radix character within the current locale.
The ecvt() and fcvt() functions return a pointer to a null-
terminated string of digits.
The gcvt() function returns buf.
No errors are defined.
The return values from ecvt() and fcvt() may point to static
data which may be overwritten by subsequent calls to these
For portability to implementations conforming to earlier
versions of this document, sprintf(3C) is preferred over
See attributes(5) for descriptions of the following attri-
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
| MT-Level | Unsafe |
printf(3C), setlocale(3C), sprintf(3C), attributes(5)
Man(1) output converted with