ecvt.3

来自「<B>Digital的Unix操作系统VAX 4.2源码</B>」· 3 代码 · 共 98 行

.\" SCCSID: @(#)ecvt.3	2.4	8/10/87
.TH ecvt 3 
.SH Name
ecvt, fcvt, gcvt \- output conversion
.SH Syntax
.nf
.B char *ecvt(\fIvalue, ndigit, decpt, sign\fP)
.B double value;
.B int \fIndigit, *decpt, *sign\fP;
.PP
.B char *fcvt(\fIvalue, ndigit, decpt, sign\fP)
.B double value;
.B int \fIndigit, *decpt, *sign\fP;
.PP
.B char *gcvt(\fIvalue, ndigit, buf\fP)
.B double value;
.B char \fI*buf\fP;
.fi
.SH Description
.NXR "ecvt subroutine"
.NXR "fcvt subroutine"
.NXR "gcvt subroutine"
.NXR "ASCII string" "converting to"
The
.PN ecvt
routine converts the 
.I value
to a null-terminated string of
.I ndigit
ASCII digits and returns a pointer thereto.
The position of the radix character relative to the
beginning of the string is stored indirectly through
.I decpt 
(negative means to the left of the returned digits).
If the sign of the result is negative, the word pointed to by
.I sign 
is non-zero, otherwise it is zero.  The low-order digit is rounded.
.PP
The
.PN fcvt 
routine 
is identical to 
.PN ecvt ,
except that the correct digit
has been rounded for FORTRAN F-format output of the number
of digits specified by
.IR \(*_ndigits .
.PP
The
.PN gcvt
routine converts the
.I value
to a null-terminated ASCII string in
.I buf
and returns a pointer to 
.I buf.
It attempts to produce
.I ndigit
significant digits in FORTRAN F format if possible, otherwise E format is
used, ready for printing.  Trailing zeros may be suppressed.
.PP
The symbol used to represent a radix character is obtained from the last
successful call to
.PN setlocale
category
.PN LC_NUMERIC .
The symbol can be determined by calling:
.EX
nl_langinfo (RADIXCHAR);
.EE
.PP
If
.PN setlocale
category
.PN LC_NUMERIC
has not been called successfully, or if the radix character is not defined for a supported language, the radix character defaults to a period (.).
.SS International Environment
.IP LC_NUMERIC 15
If this environment is set and valid, 
.PN ecvt
uses the international language database named in the definition to determine
radix character rules. 
.IP LANG 15
If this environment is set and valid, 
.PN ecvt
uses the international language database named in the definition to determine
radix character rules. If 
.PN LC_NUMERIC
is defined, its definition supercedes the definition of 
.PN LANG. 
.SH Restrictions
The return values point to static data
whose content is overwritten by each call.
.SH See Also
setlocale(3), nl_langinfo(3int), printf(3int), printf(3s)
.br
.I Guide to Developing International Software