1 '\" te
2 .\" Copyright 1989 AT&T. Copyright (c) 2004, Sun Microsystems, Inc. All Rights Reserved. Portions Copyright (c) 1992, X/Open Company Limited, All Rights Reserved.
3 .\" Sun Microsystems, Inc. gratefully acknowledges The Open Group for permission to reproduce portions of its copyrighted documentation. Original documentation from The Open Group can be obtained online at
4 .\" http://www.opengroup.org/bookstore/.
5 .\" The Institute of Electrical and Electronics Engineers and The Open Group, have given us permission to reprint portions of their documentation. In the following statement, the phrase "this text" refers to portions of the system documentation. Portions of this text are reprinted and reproduced in electronic form in the Sun OS Reference Manual, from IEEE Std 1003.1, 2004 Edition, Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2004 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the event of any discrepancy between these versions and the original IEEE and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained online at http://www.opengroup.org/unix/online.html.
6 .\" This notice shall appear on any product containing this material.
7 .\" The contents of this file are subject to the terms of the Common Development and Distribution License (the "License"). You may not use this file except in compliance with the License.
8 .\" You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE or http://www.opensolaris.org/os/licensing. See the License for the specific language governing permissions and limitations under the License.
9 .\" When distributing Covered Code, include this CDDL HEADER in each file and include the License file at usr/src/OPENSOLARIS.LICENSE. If applicable, add the following below this CDDL HEADER, with the fields enclosed by brackets "[]" replaced with your own identifying information: Portions Copyright [yyyy] [name of copyright owner]
10 .TH ECVT 3C "May 18, 2004"
11 .SH NAME
12 ecvt, fcvt, gcvt \- convert floating-point number to string
13 .SH SYNOPSIS
14 .LP
15 .nf
16 #include <stdlib.h>
17
18 \fBchar *\fR\fBecvt\fR(\fBdouble\fR \fIvalue\fR, \fBint\fR \fIndigit\fR, \fBint *restrict\fR \fIdecpt\fR, \fBint *restrict\fR \fIsign\fR);
19 .fi
20
21 .LP
22 .nf
23 \fBchar *\fR\fBfcvt\fR(\fBdouble\fR \fIvalue\fR, \fBint\fR \fIndigit\fR, \fBint *restrict\fR \fIdecpt\fR, \fBint *restrict\fR \fIsign\fR);
24 .fi
25
26 .LP
27 .nf
28 \fBchar *\fR\fBgcvt\fR(\fBdouble\fR \fIvalue\fR, \fBint\fR \fIndigit\fR, \fBchar *\fR\fIbuf\fR);
29 .fi
30
31 .SH DESCRIPTION
32 .sp
33 .LP
34 The \fBecvt()\fR, \fBfcvt()\fR and \fBgcvt()\fR functions convert
35 floating-point numbers to null-terminated strings.
36 .SS "\fBecvt()\fR"
37 .sp
38 .LP
39 The \fBecvt()\fR function converts \fIvalue\fR to a null-terminated string of
40 \fIndigit\fR digits (where \fIndigit\fR is reduced to an unspecified limit
41 determined by the precision of a \fBdouble\fR) and returns a pointer to the
42 string. The high-order digit is non-zero, unless the value is 0. The
43 low-order digit is rounded. The position of the radix character relative to
44 the beginning of the string is stored in the integer pointed to by \fIdecpt\fR
45 (negative means to the left of the returned digits). The radix character is not
46 included in the returned string. If the sign of the result is negative, the
47 integer pointed to by \fIsign\fR is non-zero, otherwise it is 0.
48 .sp
49 .LP
50 If the converted value is out of range or is not representable, the contents of
51 the returned string are unspecified.
52 .SS "\fBfcvt()\fR"
53 .sp
54 .LP
55 The \fBfcvt()\fR function is identical to \fBecvt()\fR except that \fIndigit\fR
56 specifies the number of digits desired after the radix point. The total number
57 of digits in the result string is restricted to an unspecified limit as
58 determined by the precision of a \fBdouble\fR.
59 .SS "\fBgcvt()\fR"
60 .sp
61 .LP
62 The \fBgcvt()\fR function converts \fIvalue\fR to a null-terminated string
63 (similar to that of the \fB%g\fR format of \fBprintf\fR(3C)) in the array
64 pointed to by \fIbuf\fR and returns \fIbuf\fR. It produces \fIndigit\fR
65 significant digits (limited to an unspecified value determined by the precision
66 of a \fBdouble\fR) in \fB%f\fR if possible, or \fB%e\fR (scientific notation)
67 otherwise. A minus sign is included in the returned string if \fIvalue\fR is
68 less than 0. A radix character is included in the returned string if
69 \fIvalue\fR is not a whole number. Trailing zeros are suppressed where
70 \fIvalue\fR is not a whole number. The radix character is determined by the
71 current locale. If \fBsetlocale\fR(3C) has not been called successfully, the
72 default locale, POSIX, is used. The default locale specifies a period
73 (\fB\&.\fR) as the radix character. The \fBLC_NUMERIC\fR category determines
74 the value of the radix character within the current locale.
75 .SH RETURN VALUES
76 .sp
77 .LP
78 The \fBecvt()\fR and \fBfcvt()\fR functions return a pointer to a
79 null-terminated string of digits.
80 .sp
81 .LP
82 The \fBgcvt()\fR function returns \fIbuf\fR.
83 .SH ERRORS
84 .sp
85 .LP
86 No errors are defined.
87 .SH USAGE
88 .sp
89 .LP
90 The return values from \fBecvt()\fR and \fBfcvt()\fR might point to
91 thread-specific data that can be overwritten by subsequent calls to these
92 functions by the same thread.
93 .sp
94 .LP
95 For portability to implementations conforming to earlier versions of Solaris,
96 \fBsprintf\fR(3C) is preferred over this function.
97 .SH ATTRIBUTES
98 .sp
99 .LP
100 See \fBattributes\fR(5) for descriptions of the following attributes:
101 .sp
102
103 .sp
104 .TS
105 box;
106 c | c
107 l | l .
108 ATTRIBUTE TYPE ATTRIBUTE VALUE
109 _
110 Interface Stability Standard
111 _
112 MT-Level Safe
113 .TE
114
115 .SH SEE ALSO
116 .sp
117 .LP
118 \fBprintf\fR(3C), \fBsetlocale\fR(3C), \fBsprintf\fR(3C), \fBattributes\fR(5),
119 \fBstandards\fR(5)
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1 .\" Copyright 2014 Garrett D'Amore <garrett@damore.org>
2 .\" Copyright 1989 AT&T. Copyright (c) 2004, Sun Microsystems, Inc. All Rights Reserved. Portions Copyright (c) 1992, X/Open Company Limited, All Rights Reserved.
3 .\" Sun Microsystems, Inc. gratefully acknowledges The Open Group for permission to reproduce portions of its copyrighted documentation. Original documentation from The Open Group can be obtained online at
4 .\" http://www.opengroup.org/bookstore/.
5 .\" The Institute of Electrical and Electronics Engineers and The Open Group, have given us permission to reprint portions of their documentation. In the following statement, the phrase "this text" refers to portions of the system documentation. Portions of this text are reprinted and reproduced in electronic form in the Sun OS Reference Manual, from IEEE Std 1003.1, 2004 Edition, Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2004 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the event of any discrepancy between these versions and the original IEEE and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained online at http://www.opengroup.org/unix/online.html.
6 .\" This notice shall appear on any product containing this material.
7 .\" The contents of this file are subject to the terms of the Common Development and Distribution License (the "License"). You may not use this file except in compliance with the License.
8 .\" You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE or http://www.opensolaris.org/os/licensing. See the License for the specific language governing permissions and limitations under the License.
9 .\" When distributing Covered Code, include this CDDL HEADER in each file and include the License file at usr/src/OPENSOLARIS.LICENSE. If applicable, add the following below this CDDL HEADER, with the fields enclosed by brackets "[]" replaced with your own identifying information: Portions Copyright [yyyy] [name of copyright owner]
10 .Dd "Jul 19, 2014"
11 .Dt ECVT 3C
12 .Os
13 .Sh NAME
14 .Nm ecvt, fcvt, gcvt
15 .Nd convert floating-point number to string
16 .Sh SYNOPSIS
17 .In stdlib.h
18 .Ft "char *"
19 .Fn ecvt "double value" "int ndigit" "int *restrict decpt" "int *restrict sign"
20 .Ft "char *"
21 .Fn fcvt "double value" "int ndigit" "int *restrict decpt" "int *restrict sign"
22 .Ft "char *"
23 .Fn gcvt "double value" "int ndigit" "char *buf"
24 .Sh DESCRIPTION
25 The
26 .Fn ecvt ,
27 .Fn fcvt ,
28 and
29 .Fn gcvt
30 functions convert floating-point numbers to null-terminated strings.
31 .Ss Fn ecvt
32 The
33 .Fn ecvt
34 function converts
35 .Fa value
36 to a null-terminated string of
37 .Fa ndigit
38 digits (where
39 .Fa ndigit
40 is reduced to an unspecified limit determined by the precision of a
41 .Ft double
42 and returns a pointer to the
43 string. The high-order digit is non-zero, unless the value is 0. The
44 low-order digit is rounded. The position of the radix character relative to
45 the beginning of the string is stored in the integer pointed to by
46 .Fa decpt
47 (negative means to the left of the returned digits). The radix character is not
48 included in the returned string. If the sign of the result is negative, the
49 integer pointed to by
50 .Fa sign
51 is non-zero, otherwise it is 0.
52 .Lp
53 If the converted value is out of range or is not representable, the contents of
54 the returned string are unspecified.
55 .Ss Fn fcvt
56 The
57 .Fn fcvt
58 function is identical to
59 .Fn ecvt
60 except that
61 .Fa ndigit
62 specifies the number of digits desired after the radix point. The total number
63 of digits in the result string is restricted to an unspecified limit as
64 determined by the precision of a
65 .Ft double .
66 .Ss Fn gcvt
67 The
68 .Fn gcvt
69 function converts
70 .Fa value
71 to a null-terminated string
72 (similar to that of the
73 .Em %g
74 format of
75 .Xr printf 3C
76 in the array pointed to by
77 .Fa buf
78 and returns
79 .Fa buf .
80 It produces
81 .Fa ndigit
82 significant digits (limited to an unspecified value determined by the precision
83 of a
84 .Ft double )
85 in
86 .Em %f
87 if possible, or
88 .Em %e
89 (scientific notation)
90 otherwise. A minus sign is included in the returned string if
91 .Fa value
92 is less than 0. A radix character is included in the returned string if
93 .Fa value
94 is not a whole number. Trailing zeros are suppressed where
95 .Fa value
96 is not a whole number. The radix character is determined by the
97 .Dv LC_NUMERIC
98 category of the current locale. In the default, POSIX, locale, the period
99 .Pq Em \&.
100 is used for the radix character.
101 default locale, POSIX, is used.
102 .Sh RETURN VALUES
103 The
104 .Fn ecvt
105 and
106 .Fn fcvt
107 functions return a pointer to a null-terminated string of digits.
108 .Lp
109 The
110 .Fn gcvt
111 function returns
112 .Fa buf .
113 .Sh ERRORS
114 No errors are defined.
115 .Sh USAGE
116 The return values from
117 .Fn ecvt
118 and
119 .Fn fcvt
120 might point to
121 thread-specific data that can be overwritten by subsequent calls to these
122 functions by the same thread.
123 .Lp
124 Portable applications should use
125 .Xr sprintf 3C ,
126 which is mandated by
127 .St -isoC .
128 .Sh INTERFACE STABILITY
129 .Sy Obsolete Standard .
130 .Sh MT-LEVEL
131 .Sy Safe .
132 .Sh SEE ALSO
133 .Xr printf 3C ,
134 .Xr setlocale 3C
135 .Xr sprintf 3C ,
136 .Xr standards 5
137 .Sh STANDARDS
138 These functions were introduced in
139 .St -xpg4.2 .
140 They were obsoleted in
141 .St -p1003.1-2001
142 and removed from
143 .St -p1003.1-2008 .
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