1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
|
.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
.\"
.\" %%%LICENSE_START(VERBATIM)
.\" Permission is granted to make and distribute verbatim copies of this
.\" manual provided the copyright notice and this permission notice are
.\" preserved on all copies.
.\"
.\" Permission is granted to copy and distribute modified versions of this
.\" manual under the conditions for verbatim copying, provided that the
.\" entire resulting derived work is distributed under the terms of a
.\" permission notice identical to this one.
.\"
.\" Since the Linux kernel and libraries are constantly changing, this
.\" manual page may be incorrect or out-of-date. The author(s) assume no
.\" responsibility for errors or omissions, or for damages resulting from
.\" the use of the information contained herein. The author(s) may not
.\" have taken the same level of care in the production of this manual,
.\" which is licensed free of charge, as they might when working
.\" professionally.
.\"
.\" Formatted or processed versions of this manual, if unaccompanied by
.\" the source, must acknowledge the copyright and authors of this work.
.\" %%%LICENSE_END
.\"
.\" References consulted:
.\" Linux libc source code
.\" Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
.\" 386BSD man pages
.\" Modified Sat Jul 24 19:40:39 1993 by Rik Faith (faith@cs.unc.edu)
.\" Modified Fri Jun 25 12:10:47 1999 by Andries Brouwer (aeb@cwi.nl)
.\"
.TH ECVT 3 2016-03-15 "" "Linux Programmer's Manual"
.SH NAME
ecvt, fcvt \- convert a floating-point number to a string
.SH SYNOPSIS
.B #include <stdlib.h>
.PP
.BI "char *ecvt(double " number ", int " ndigits ", int *" decpt ,
.BI "int *" sign );
.PP
.BI "char *fcvt(double " number ", int " ndigits ", int *" decpt ,
.BI "int *" sign );
.PP
.RS -4
Feature Test Macro Requirements for glibc (see
.BR feature_test_macros (7)):
.RE
.PP
.BR ecvt (),
.BR fcvt ():
.ad l
.RS 4
.PD 0
.TP 4
Since glibc 2.12:
.nf
(_XOPEN_SOURCE\ >=\ 500) ! (_POSIX_C_SOURCE\ >=\ 200112L)
|| /* Glibc since 2.19: */ _DEFAULT_SOURCE
|| /* Glibc versions <= 2.19: */ _SVID_SOURCE
.fi
.TP 4
Before glibc 2.12:
_SVID_SOURCE || _XOPEN_SOURCE\ >=\ 500
.\" || _XOPEN_SOURCE\ &&\ _XOPEN_SOURCE_EXTENDED
.PD
.RE
.ad b
.SH DESCRIPTION
The
.BR ecvt ()
function converts \fInumber\fP to a null-terminated
string of \fIndigits\fP digits (where \fIndigits\fP is reduced to a
system-specific limit determined by the precision of a
.IR double ),
and returns a pointer to the string.
The high-order digit is nonzero, unless
.I number
is zero.
The low order digit is rounded.
The string itself does not contain a decimal point; however,
the position of the decimal point relative to the start of the string
is stored in \fI*decpt\fP.
A negative value for \fI*decpt\fP means that
the decimal point is to the left of the start of the string.
If the sign of
\fInumber\fP is negative, \fI*sign\fP is set to a nonzero value,
otherwise it is set to 0.
If
.I number
is zero, it is unspecified whether \fI*decpt\fP is 0 or 1.
.PP
The
.BR fcvt ()
function is identical to
.BR ecvt (),
except that
\fIndigits\fP specifies the number of digits after the decimal point.
.SH RETURN VALUE
Both the
.BR ecvt ()
and
.BR fcvt ()
functions return a pointer to a
static string containing the ASCII representation of \fInumber\fP.
The static string is overwritten by each call to
.BR ecvt ()
or
.BR fcvt ().
.SH ATTRIBUTES
For an explanation of the terms used in this section, see
.BR attributes (7).
.TS
allbox;
lb lb lb
l l l.
Interface Attribute Value
T{
.BR ecvt ()
T} Thread safety MT-Unsafe race:ecvt
T{
.BR fcvt ()
T} Thread safety MT-Unsafe race:fcvt
.TE
.SH CONFORMING TO
SVr2;
marked as LEGACY in POSIX.1-2001.
POSIX.1-2008 removes the specifications of
.BR ecvt ()
and
.BR fcvt (),
recommending the use of
.BR sprintf (3)
instead (though
.BR snprintf (3)
may be preferable).
.SH NOTES
.\" Linux libc4 and libc5 specified the type of
.\" .I ndigits
.\" as
.\" .IR size_t .
Not all locales use a point as the radix character ("decimal point").
.SH SEE ALSO
.BR ecvt_r (3),
.BR gcvt (3),
.BR qecvt (3),
.BR setlocale (3),
.BR sprintf (3)
.SH COLOPHON
This page is part of release 5.10 of the Linux
.I man-pages
project.
A description of the project,
information about reporting bugs,
and the latest version of this page,
can be found at
\%https://www.kernel.org/doc/man\-pages/.
|
