]>
Commit | Line | Data |
---|---|---|
fea681da MK |
1 | .\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk) |
2 | .\" | |
4b72fb64 | 3 | .\" %%%LICENSE_START(verbatim) |
fea681da MK |
4 | .\" Permission is granted to make and distribute verbatim copies of this |
5 | .\" manual provided the copyright notice and this permission notice are | |
6 | .\" preserved on all copies. | |
7 | .\" | |
8 | .\" Permission is granted to copy and distribute modified versions of this | |
9 | .\" manual under the conditions for verbatim copying, provided that the | |
10 | .\" entire resulting derived work is distributed under the terms of a | |
11 | .\" permission notice identical to this one. | |
c13182ef | 12 | .\" |
fea681da MK |
13 | .\" Since the Linux kernel and libraries are constantly changing, this |
14 | .\" manual page may be incorrect or out-of-date. The author(s) assume no | |
15 | .\" responsibility for errors or omissions, or for damages resulting from | |
16 | .\" the use of the information contained herein. The author(s) may not | |
17 | .\" have taken the same level of care in the production of this manual, | |
18 | .\" which is licensed free of charge, as they might when working | |
19 | .\" professionally. | |
c13182ef | 20 | .\" |
fea681da MK |
21 | .\" Formatted or processed versions of this manual, if unaccompanied by |
22 | .\" the source, must acknowledge the copyright and authors of this work. | |
4b72fb64 | 23 | .\" %%%LICENSE_END |
fea681da MK |
24 | .\" |
25 | .\" References consulted: | |
26 | .\" Linux libc source code | |
27 | .\" Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991) | |
28 | .\" 386BSD man pages | |
29 | .\" Modified Sat Jul 24 19:40:39 1993 by Rik Faith (faith@cs.unc.edu) | |
30 | .\" Modified Fri Jun 25 12:10:47 1999 by Andries Brouwer (aeb@cwi.nl) | |
31 | .\" | |
50831f9b | 32 | .TH ECVT 3 2010-09-20 "" "Linux Programmer's Manual" |
fea681da MK |
33 | .SH NAME |
34 | ecvt, fcvt \- convert a floating-point number to a string | |
35 | .SH SYNOPSIS | |
36 | .B #include <stdlib.h> | |
37 | .sp | |
38 | .BI "char *ecvt(double " number ", int " ndigits ", int *" decpt , | |
39 | .BI "int *" sign ); | |
40 | .sp | |
41 | .BI "char *fcvt(double " number ", int " ndigits ", int *" decpt , | |
42 | .BI "int *" sign ); | |
cc4615cc MK |
43 | .sp |
44 | .in -4n | |
45 | Feature Test Macro Requirements for glibc (see | |
46 | .BR feature_test_macros (7)): | |
47 | .in | |
48 | .sp | |
49 | .BR ecvt (), | |
50 | .BR fcvt (): | |
4943de06 MK |
51 | .ad l |
52 | .RS 4 | |
53 | .PD 0 | |
54 | .TP 4 | |
55 | Since glibc 2.12: | |
56 | .nf | |
57 | _SVID_SOURCE || | |
98dbe7af | 58 | (_XOPEN_SOURCE\ >=\ 500 || |
7b072c4d | 59 | _XOPEN_SOURCE\ &&\ _XOPEN_SOURCE_EXTENDED) && |
98dbe7af | 60 | !(_POSIX_C_SOURCE\ >=\ 200112L || _XOPEN_SOURCE\ >=\ 600) |
4943de06 MK |
61 | .fi |
62 | .TP 4 | |
63 | Before glibc 2.12: | |
98dbe7af MK |
64 | _SVID_SOURCE || _XOPEN_SOURCE\ >=\ 500 || |
65 | _XOPEN_SOURCE\ &&\ _XOPEN_SOURCE_EXTENDED | |
4943de06 MK |
66 | .PD |
67 | .RE | |
68 | .ad b | |
fea681da | 69 | .SH DESCRIPTION |
60a90ecd MK |
70 | The |
71 | .BR ecvt () | |
72 | function converts \fInumber\fP to a null-terminated | |
3c5e62b6 | 73 | string of \fIndigits\fP digits (where \fIndigits\fP is reduced to a |
6d275e3c MK |
74 | system-specific limit determined by the precision of a |
75 | .IR double ), | |
c13182ef | 76 | and returns a pointer to the string. |
c7094399 | 77 | The high-order digit is nonzero, unless |
fea681da | 78 | .I number |
c13182ef MK |
79 | is zero. |
80 | The low order digit is rounded. | |
fea681da MK |
81 | The string itself does not contain a decimal point; however, |
82 | the position of the decimal point relative to the start of the string | |
8c1a40ca MK |
83 | is stored in \fI*decpt\fP. |
84 | A negative value for \fI*decpt\fP means that | |
c13182ef MK |
85 | the decimal point is to the left of the start of the string. |
86 | If the sign of | |
c7094399 | 87 | \fInumber\fP is negative, \fI*sign\fP is set to a nonzero value, |
3758f6da | 88 | otherwise it is set to 0. |
c13182ef | 89 | If |
fea681da | 90 | .I number |
8c1a40ca | 91 | is zero, it is unspecified whether \fI*decpt\fP is 0 or 1. |
fea681da | 92 | .PP |
60a90ecd MK |
93 | The |
94 | .BR fcvt () | |
95 | function is identical to | |
96 | .BR ecvt (), | |
97 | except that | |
fea681da | 98 | \fIndigits\fP specifies the number of digits after the decimal point. |
47297adb | 99 | .SH RETURN VALUE |
60a90ecd MK |
100 | Both the |
101 | .BR ecvt () | |
102 | and | |
103 | .BR fcvt () | |
104 | functions return a pointer to a | |
fea681da | 105 | static string containing the ASCII representation of \fInumber\fP. |
60a90ecd MK |
106 | The static string is overwritten by each call to |
107 | .BR ecvt () | |
108 | or | |
109 | .BR fcvt (). | |
47297adb | 110 | .SH CONFORMING TO |
2b2581ee MK |
111 | SVr2; |
112 | marked as LEGACY in POSIX.1-2001. | |
2ce94173 MK |
113 | POSIX.1-2008 removes the specifications of |
114 | .BR ecvt () | |
115 | and | |
5a466811 MK |
116 | .BR fcvt (), |
117 | recommending the use of | |
fb186734 | 118 | .BR sprintf (3) |
5a466811 MK |
119 | instead (though |
120 | .BR snprintf (3) | |
121 | may be preferable). | |
122 | .SH NOTES | |
fea681da MK |
123 | Linux libc4 and libc5 specified the type of |
124 | .I ndigits | |
125 | as | |
f19a0f03 | 126 | .IR size_t . |
2d986c92 | 127 | Not all locales use a point as the radix character ("decimal point"). |
47297adb | 128 | .SH SEE ALSO |
fea681da MK |
129 | .BR ecvt_r (3), |
130 | .BR gcvt (3), | |
131 | .BR qecvt (3), | |
132 | .BR setlocale (3), | |
133 | .BR sprintf (3) |