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46 .TH WCSTOD 3C "Mar 31, 2003"
47 .SH NAME
48 wcstod, wcstof, wcstold, wstod, watof \- convert wide character string to
49 floating-point number
50 .SH SYNOPSIS
51 .LP
52 .nf
53 #include <wchar.h>
54
55 \fBdouble\fR \fBwcstod\fR(\fBconst wchar_t *restrict\fR \fInptr\fR,
56 \fBwchar_t **restrict\fR \fIendptr\fR);
57 .fi
58
59 .LP
60 .nf
61 \fBfloat\fR \fBwcstof\fR(\fBconst wchar_t *restrict\fR \fInptr\fR,
62 \fBwchar_t **restrict\fR \fIendptr\fR);
63 .fi
64
65 .LP
66 .nf
67 \fBlong double\fR \fBwcstold\fR(\fBconst wchar_t *restrict\fR \fInptr\fR,
68 \fBwchar_t **restrict\fR \fIendptr\fR);
69 .fi
70
71 .LP
72 .nf
73 \fBdouble\fR \fBwstod\fR(\fBconst wchar_t *\fR\fInptr\fR, \fBwchar_t **\fR\fIendptr\fR);
74 .fi
75
76 .LP
77 .nf
78 \fBdouble\fR \fBwatof\fR(\fBwchar_t *\fR\fInptr\fR);
79 .fi
80
81 .SH DESCRIPTION
82 .sp
83 .LP
84 The \fBwcstod()\fR, \fBwcstof()\fR, and \fBwcstold()\fR functions convert the
85 initial portion of the wide-character string pointed to by \fInptr\fR to
86 \fBdouble\fR, \fBfloat\fR, and \fBlong double\fR representation, respectively.
87 They first decompose the input wide-character string into three parts:
88 .RS +4
89 .TP
90 1.
91 An initial, possibly empty, sequence of white-space wide-character codes (as
92 specified by \fBiswspace\fR(3C))
93 .RE
94 .RS +4
95 .TP
96 2.
97 A subject sequence interpreted as a floating-point constant or representing
98 infinity or NaN
99 .RE
100 .RS +4
101 .TP
102 3.
103 A final wide-character string of one or more unrecognized wide-character
104 codes, including the terminating null wide-character code of the input
105 wide-character string.
106 .RE
107 .sp
108 .LP
109 Then they attempt to convert the subject sequence to a floating-point number,
110 and return the result.
111 .sp
112 .LP
113 The expected form of the subject sequence is an optional plus or minus sign,
114 then one of the following:
115 .RS +4
116 .TP
117 .ie t \(bu
118 .el o
119 A non-empty sequence of decimal digits optionally containing a radix character,
120 then an optional exponent part
121 .RE
122 .RS +4
123 .TP
124 .ie t \(bu
125 .el o
126 A 0x or 0X, then a non-empty sequence of hexadecimal digits optionally
127 containing a radix character, then an optional binary exponent part
128 .RE
129 .RS +4
130 .TP
131 .ie t \(bu
132 .el o
133 One of INF or INFINITY, or any other wide string equivalent except for case
134 .RE
135 .RS +4
136 .TP
137 .ie t \(bu
138 .el o
139 One of NAN or NAN(\fIn-wchar-sequence\fR(\fIopt\fR)), or any other wide string
140 ignoring case in the NAN part, where:
141 .sp
142 .in +2
143 .nf
144 n-wchar-sequence:
145 digit
146 nondigit
147 n-wchar-sequence digit
148 n-wchar-sequence nondigit
149 .fi
150 .in -2
151
152 .RE
153 .sp
154 .LP
155 In default mode for \fBwcstod()\fR, only decimal, INF/INFINITY, and
156 NAN/NAN(\fIn-char-sequence\fR) forms are recognized. In C99/SUSv3 mode,
157 hexadecimal strings are also recognized.
158 .sp
159 .LP
160 In default mode for \fBwcstod()\fR, the \fIn-char-sequence\fR in the
161 NAN(\fIn-char-equence\fR) form can contain any character except ')' (right
162 parenthesis) or '\e0' (null). In C99/SUSv3 mode, the \fIn-char-sequence\fR can
163 contain only upper and lower case letters, digits, and '_' (underscore).
164 .sp
165 .LP
166 The \fBwcstof()\fR and \fBwcstold()\fR functions always function in
167 C99/SUSv3-conformant mode.
168 .sp
169 .LP
170 The subject sequence is defined as the longest initial subsequence of the input
171 wide string, starting with the first non-white-space wide character, that is of
172 the expected form. The subject sequence contains no wide characters if the
173 input wide string is not of the expected form.
174 .sp
175 .LP
176 If the subject sequence has the expected form for a floating-point number, the
177 sequence of wide characters starting with the first digit or the radix
178 character (whichever occurs first) is interpreted as a floating constant
179 according to the rules of the C language, except that the radix character is
180 used in place of a period, and that if neither an exponent part nor a radix
181 character appears in a decimal floating-point number, or if a binary exponent
182 part does not appear in a hexadecimal floating-point number, an exponent part
183 of the appropriate type with value zero is assumed to follow the last digit in
184 the string. If the subject sequence begins with a minus sign, the sequence is
185 interpreted as negated. A wide-character sequence INF or INFINITY is
186 interpreted as an infinity. A wide-character sequence NAN or
187 NAN(\fIn-wchar-sequence\fR(\fIopt\fR)) is interpreted as a quiet NaN. A pointer
188 to the final wide string is stored in the object pointed to by \fIendptr\fR,
189 provided that \fIendptr\fR is not a null pointer.
190 .sp
191 .LP
192 If the subject sequence has either the decimal or hexadecimal form, the value
193 resulting from the conversion is rounded correctly according to the prevailing
194 floating point rounding direction mode. The conversion also raises floating
195 point inexact, underflow, or overflow exceptions as appropriate.
196 .sp
197 .LP
198 The radix character is defined in the program's locale (category
199 \fBLC_NUMERIC\fR). In the POSIX locale, or in a locale where the radix
200 character is not defined, the radix character defaults to a period ('.').
201 .sp
202 .LP
203 If the subject sequence is empty or does not have the expected form, no
204 conversion is performed; the value of \fInptr\fR is stored in the object
205 pointed to by \fIendptr\fR, provided that \fIendptr\fR is not a null pointer.
206 .sp
207 .LP
208 The \fBwcstod()\fR function does not change the setting of \fBerrno\fR if
209 successful.
210 .sp
211 .LP
212 The \fBwstod()\fR function is identical to \fBwcstod()\fR.
213 .sp
214 .LP
215 The \fBwatof\fR(\fIstr\fR) function is equivalent to \fBwstod(\fR\fInptr\fR\fB,
216 (wchar_t **)NULL)\fR.
217 .SH RETURN VALUES
218 .sp
219 .LP
220 Upon successful completion, these functions return the converted value. If no
221 conversion could be performed, \fB0\fR is returned.
222 .sp
223 .LP
224 If the correct value is outside the range of representable values,
225 \fB\(+-HUGE_VAL\fR, \fB\(+-HUGE_VALF\fR, or \fB\(+-HUGE_VALL\fR is returned
226 (according to the sign of the value), a floating point overflow exception is
227 raised, and \fBerrno\fR is set to \fBERANGE\fR.
228 .sp
229 .LP
230 If the correct value would cause an underflow, the correctly rounded result
231 (which may be normal, subnormal, or zero) is returned, a floating point
232 underflow exception is raised, and \fBerrno\fR is set to \fBERANGE\fR.
233 .SH ERRORS
234 .sp
235 .LP
236 The \fBwcstod()\fR and \fBwstod()\fR functions will fail if:
237 .sp
238 .ne 2
239 .na
240 \fB\fBERANGE\fR\fR
241 .ad
242 .RS 10n
243 The value to be returned would cause overflow or underflow.
244 .RE
245
246 .sp
247 .LP
248 The \fBwcstod()\fR and \fBwcstod()\fR functions may fail if:
249 .sp
250 .ne 2
251 .na
252 \fB\fBEINVAL\fR\fR
253 .ad
254 .RS 10n
255 No conversion could be performed.
256 .RE
257
258 .SH USAGE
259 .sp
260 .LP
261 Because 0 is returned on error and is also a valid return on success, an
262 application wishing to check for error situations should set \fBerrno\fR to 0
263 call \fBwcstod()\fR, \fBwcstof()\fR, \fBwcstold()\fR, or \fBwstod()\fR, then
264 check \fBerrno\fR and if it is non-zero, assume an error has occurred.
265 .SH ATTRIBUTES
266 .sp
267 .LP
268 See \fBattributes\fR(5) for descriptions of the following attributes:
269 .sp
270
271 .sp
272 .TS
273 box;
274 l | l
275 l | l .
276 ATTRIBUTE TYPE ATTRIBUTE VALUE
277 _
278 Interface Stability T{
279 \fBwcstod()\fR, \fBwcstof()\fR, and \fBwcstold()\fR are Standard.
280 T}
281 _
282 MT-Level MT-Safe
283 .TE
284
285 .SH SEE ALSO
286 .sp
287 .LP
288 \fBiswspace\fR(3C), \fBlocaleconv\fR(3C), \fBscanf\fR(3C), \fBsetlocale\fR(3C),
289 \fBwcstol\fR(3C), \fBattributes\fR(5), \fBstandards\fR(5)