ecvt(3) BSD Library Functions Manual ecvt(3)
NAME
ecvt, fcvt, gcvt -- convert double to ASCII 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
These functions are provided for compatibility with legacy code. New
code should use the snprintf(3) function for improved safety and porta-
bility.
The ecvt(), fcvt() and gcvt() functions convert the double precision
floating-point number value to a NUL-terminated ASCII string.
The ecvt() function converts value to a NUL-terminated string of exactly
ndigit digits and returns a pointer to that string. The result is padded
with zeroes from left to right as needed. There are no leading zeroes
unless value itself is 0. The least significant digit is rounded in an
implementation-dependent manner. The position of the decimal point rela-
tive to the beginning of the string is stored in decpt. A negative value
indicates that the decimal point is located to the left of the returned
digits (this occurs when there is no whole number component to value).
If value is zero, it is unspecified whether the integer pointed to by
decpt will be 0 or 1. The decimal point itself 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 con-
tents of the returned string are unspecified.
The fcvt() function is identical to ecvt() with the exception that ndigit
specifies the number of digits after the decimal point (zero-padded as
needed).
The gcvt() function converts value to a NUL-terminated string similar to
the %g printf(3) format specifier and stores the result in buf. It pro-
duces ndigit significant digits similar to the %f printf(3) format speci-
fier where possible. If ndigit does allow sufficient precision, the
result is stored in exponential notation similar to the %e printf(3) for-
mat specifier. If value is less than zero, buf will be prefixed with a
minus sign. A decimal point is included in the returned string if value
is not a whole number. Unlike the ecvt() and fcvt() functions, buf is
not zero-padded.
RETURN VALUES
The ecvt(), fcvt() and gcvt() functions return a NUL-terminated string
representation of value.
WARNINGS
The ecvt() and fcvt() functions return a pointer to internal storage
space that will be overwritten by subsequent calls to either function.
The maximum possible precision of the return value is limited by the pre-
cision of a double and may not be the same on all architectures.
The snprintf(3) function is preferred over these functions for new code.
SEE ALSO
printf(3), strtod(3)
STANDARDS
The ecvt(), fcvt() and gcvt() functions conform to IEEE Std 1003.1-2001
(``POSIX.1'').
BSD August 27, 2012 BSD
Mac OS X 10.8 - Generated Mon Aug 27 16:20:50 CDT 2012