econvert(3C) Standard C Library Functions econvert(3C)
econvert, fconvert, gconvert, seconvert, sfconvert, sgconvert, qecon‐
vert, qfconvert, qgconvert - output conversion
#include <floatingpoint.h>
char *econvert(double value, int ndigit, int *decpt, int *sign, char
*buf);
char *fconvert(double value, int ndigit, int *decpt, int *sign, char
*buf);
char *gconvert(double value, int ndigit, int trailing, char *buf);
char *seconvert(single *value, int ndigit, int *decpt, int *sign, char
*buf);
char *sfconvert(single *value, int ndigit, int *decpt, int *sign, char
*buf);
char *sgconvert(single *value, int ndigit, int trailing, char *buf);
char *qeconvert(quadruple *value, int ndigit, int *decpt, int *sign,
char *buf);
char *qfconvert(quadruple *value, int ndigit, int *decpt, int *sign,
char *buf);
char *qgconvert(quadruple *value, int ndigit, int trailing, char *buf);
The econvert() function converts the value to a null-terminated string
of ndigit ASCII digits in buf and returns a pointer to buf. buf should
contain at least ndigit+1 characters. The position of the decimal point
relative to the beginning of the string is stored indirectly through
decpt. Thus buf == "314" and *decpt == 1 corresponds to the numerical
value 3.14, while buf == "314" and *decpt == −1 corresponds to the
numerical value .0314. If the sign of the result is negative, the word
pointed to by sign is nonzero; otherwise it is zero. The least signif‐
icant digit is rounded.
The fconvert() function works much like econvert(), except that the
correct digit has been rounded as if for sprintf(%w.nf) output with
n=ndigit digits to the right of the decimal point. ndigit can be nega‐
tive to indicate rounding to the left of the decimal point. The return
value is a pointer to buf. buf should contain at least
310+max(0,ndigit) characters to accomodate any double-precision value.
The gconvert() function converts the value to a null-terminated ASCII
string in buf and returns a pointer to buf. It produces ndigit signifi‐
cant digits in fixed-decimal format, like sprintf(%w.nf), if possible,
and otherwise in floating-decimal format, like sprintf(%w.ne); in
either case buf is ready for printing, with sign and exponent. The
result corresponds to that obtained by
(void) sprintf(buf,‘‘%w.ng’’,value) ;
If trailing = 0, trailing zeros and a trailing point are suppressed, as
in sprintf(%g). If trailing != 0, trailing zeros and a trailing point
are retained, as in sprintf(%#g).
The seconvert(), sfconvert(), and sgconvert() functions are single-pre‐
cision versions of these functions, and are more efficient than the
corresponding double-precision versions. A pointer rather than the
value itself is passed to avoid C’s usual conversion of single-preci‐
sion arguments to double.
The qeconvert(), qfconvert(), and qgconvert() functions are quadruple-
precision versions of these functions. The qfconvert() function can
overflow the decimal_record field ds if value is too large. In that
case, buf[0] is set to zero.
The ecvt(), fcvt() and gcvt() functions are versions of econvert(),
fconvert(), and gconvert(), respectively, that are documented on the
ecvt(3C) manual page. They constitute the default implementation of
these functions and conform to the X/Open CAE Specification, System
Interfaces and Headers, Issue 4, Version 2.
IEEE Infinities and NaNs are treated similarly by these functions.
‘‘NaN’’ is returned for NaN, and ‘‘Inf’’ or ‘‘Infinity’’ for Infinity.
The longer form is produced when ndigit >= 8.
See attributes (5) for descriptions of the following attributes:
+-----------------------------+-----------------------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+-----------------------------+-----------------------------+
|MT-Level |MT-Safe |
+-----------------------------+-----------------------------+
ecvt(3C),sprintf(3C), attributes(5)
SunOS 5.9 3 May 1999 econvert(3C)