ecvt(3C) Standard C Library Functions ecvt(3C)NAME
ecvt, fcvt, gcvt - convert floating-point number to string
SYNOPSIS
#include <stdlib.h>
char *ecvt(double value, int ndigit, int *restrict decpt, int *restrict
sign);
char *fcvt(double value, int ndigit, int *restrict decpt, int *restrict
sign);
char *gcvt(double value, int ndigit, char *buf);
DESCRIPTION
The ecvt(), fcvt() and gcvt() functions convert floating-point numbers
to null-terminated strings.
ecvt()
The ecvt() function converts value to a null-terminated string of
ndigit digits (where ndigit is reduced to an unspecified limit deter‐
mined 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 rounded. The position of the radix character rela‐
tive to the beginning 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 representable, the
contents of the returned string are unspecified.
fcvt()
The fcvt() function is identical to ecvt() except that ndigit 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 precision of a double.
gcvt()
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 char‐
acter is included in the returned string if value is not a whole num‐
ber. Trailing zeros are suppressed where value is not a whole number.
The radix character is determined by the current locale. If setlo‐
cale(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 char‐
acter within the current locale.
RETURN VALUES
The ecvt() and fcvt() functions return a pointer to a null-terminated
string of digits.
The gcvt() function returns buf.
ERRORS
No errors are defined.
USAGE
The return values from ecvt() and fcvt() might point to thread-specific
data that can be overwritten by subsequent calls to these functions by
the same thread.
For portability to implementations conforming to earlier versions of
Solaris, sprintf(3C) is preferred over this function.
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
┌─────────────────────────────┬─────────────────────────────┐
│ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
├─────────────────────────────┼─────────────────────────────┤
│Interface Stability │Standard │
├─────────────────────────────┼─────────────────────────────┤
│MT-Level │Safe │
└─────────────────────────────┴─────────────────────────────┘
SEE ALSOprintf(3C), setlocale(3C), sprintf(3C), attributes(5), standards(5)SunOS 5.10 18 May 2004 ecvt(3C)
