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All Rights Reserved 45 .\" 46 .TH WCSTOD 3C "Aug 25, 2019" 47 .SH NAME 48 wcstod, wcstof, wcstold, wstod, watof \- convert wide character string to 49 floating-point number 50 .SH SYNOPSIS 51 .nf 52 #include <wchar.h> 53 54 \fBdouble\fR \fBwcstod\fR(\fBconst wchar_t *restrict\fR \fInptr\fR, 55 \fBwchar_t **restrict\fR \fIendptr\fR); 56 .fi 57 58 .LP 59 .nf 60 \fBfloat\fR \fBwcstof\fR(\fBconst wchar_t *restrict\fR \fInptr\fR, 61 \fBwchar_t **restrict\fR \fIendptr\fR); 62 .fi 63 64 .LP 65 .nf 66 \fBlong double\fR \fBwcstold\fR(\fBconst wchar_t *restrict\fR \fInptr\fR, 67 \fBwchar_t **restrict\fR \fIendptr\fR); 68 .fi 69 70 .LP 71 .nf 72 \fBdouble\fR \fBwstod\fR(\fBconst wchar_t *\fR\fInptr\fR, \fBwchar_t **\fR\fIendptr\fR); 73 .fi 74 75 .LP 76 .nf 77 \fBdouble\fR \fBwatof\fR(\fBwchar_t *\fR\fInptr\fR); 78 .fi 79 80 .SH DESCRIPTION 81 The \fBwcstod()\fR, \fBwcstof()\fR, and \fBwcstold()\fR functions convert the 82 initial portion of the wide-character string pointed to by \fInptr\fR to 83 \fBdouble\fR, \fBfloat\fR, and \fBlong double\fR representation, respectively. 84 They first decompose the input wide-character string into three parts: 85 .RS +4 86 .TP 87 1. 88 An initial, possibly empty, sequence of white-space wide-character codes (as 89 specified by \fBiswspace\fR(3C)) 90 .RE 91 .RS +4 92 .TP 93 2. 94 A subject sequence interpreted as a floating-point constant or representing 95 infinity or NaN 96 .RE 97 .RS +4 98 .TP 99 3. 100 A final wide-character string of one or more unrecognized wide-character 101 codes, including the terminating null wide-character code of the input 102 wide-character string. 103 .RE 104 .sp 105 .LP 106 Then they attempt to convert the subject sequence to a floating-point number, 107 and return the result. 108 .sp 109 .LP 110 The expected form of the subject sequence is an optional plus or minus sign, 111 then one of the following: 112 .RS +4 113 .TP 114 .ie t \(bu 115 .el o 116 A non-empty sequence of decimal digits optionally containing a radix character, 117 then an optional exponent part 118 .RE 119 .RS +4 120 .TP 121 .ie t \(bu 122 .el o 123 A 0x or 0X, then a non-empty sequence of hexadecimal digits optionally 124 containing a radix character, then an optional binary exponent part 125 .RE 126 .RS +4 127 .TP 128 .ie t \(bu 129 .el o 130 One of INF or INFINITY, or any other wide string equivalent except for case 131 .RE 132 .RS +4 133 .TP 134 .ie t \(bu 135 .el o 136 One of NAN or NAN(\fIn-wchar-sequence\fR(\fIopt\fR)), or any other wide string 137 ignoring case in the NAN part, where: 138 .sp 139 .in +2 140 .nf 141 n-wchar-sequence: 142 digit 143 nondigit 144 n-wchar-sequence digit 145 n-wchar-sequence nondigit 146 .fi 147 .in -2 148 149 .RE 150 .sp 151 .LP 152 In default mode for \fBwcstod()\fR, only decimal, INF/INFINITY, and 153 NAN/NAN(\fIn-wchar-sequence\fR) forms are recognized. In C99/SUSv3 mode, 154 hexadecimal strings are also recognized. 155 .sp 156 .LP 157 In default mode for \fBwcstod()\fR, the \fIn-wchar-sequence\fR in the 158 NAN(\fIn-wchar-sequence\fR) form can contain any character except ')' (right 159 parenthesis) or '\e0' (null). In C99/SUSv3 mode, the \fIn-wchar-sequence\fR can 160 contain only upper and lower case letters, digits, and '_' (underscore). 161 .sp 162 .LP 163 The \fBwcstof()\fR and \fBwcstold()\fR functions always function in 164 C99/SUSv3-conformant mode. 165 .sp 166 .LP 167 The subject sequence is defined as the longest initial subsequence of the input 168 wide string, starting with the first non-white-space wide character, that is of 169 the expected form. The subject sequence contains no wide characters if the 170 input wide string is not of the expected form. 171 .sp 172 .LP 173 If the subject sequence has the expected form for a floating-point number, the 174 sequence of wide characters starting with the first digit or the radix 175 character (whichever occurs first) is interpreted as a floating constant 176 according to the rules of the C language, except that the radix character is 177 used in place of a period, and that if neither an exponent part nor a radix 178 character appears in a decimal floating-point number, or if a binary exponent 179 part does not appear in a hexadecimal floating-point number, an exponent part 180 of the appropriate type with value zero is assumed to follow the last digit in 181 the string. If the subject sequence begins with a minus sign, the sequence is 182 interpreted as negated. A wide-character sequence INF or INFINITY is 183 interpreted as an infinity. A wide-character sequence NAN or 184 NAN(\fIn-wchar-sequence\fR(\fIopt\fR)) is interpreted as a quiet NaN. A pointer 185 to the final wide string is stored in the object pointed to by \fIendptr\fR, 186 provided that \fIendptr\fR is not a null pointer. 187 .sp 188 .LP 189 If the subject sequence has either the decimal or hexadecimal form, the value 190 resulting from the conversion is rounded correctly according to the prevailing 191 floating point rounding direction mode. The conversion also raises floating 192 point inexact, underflow, or overflow exceptions as appropriate. 193 .sp 194 .LP 195 The radix character is defined in the program's locale (category 196 \fBLC_NUMERIC\fR). In the POSIX locale, or in a locale where the radix 197 character is not defined, the radix character defaults to a period ('.'). 198 .sp 199 .LP 200 If the subject sequence is empty or does not have the expected form, no 201 conversion is performed; the value of \fInptr\fR is stored in the object 202 pointed to by \fIendptr\fR, provided that \fIendptr\fR is not a null pointer. 203 .sp 204 .LP 205 The \fBwcstod()\fR function does not change the setting of \fBerrno\fR if 206 successful. 207 .sp 208 .LP 209 The \fBwstod()\fR function is identical to \fBwcstod()\fR. 210 .sp 211 .LP 212 The \fBwatof\fR(\fIstr\fR) function is equivalent to \fBwstod(\fR\fInptr\fR\fB, 213 (wchar_t **)NULL)\fR. 214 .SH RETURN VALUES 215 Upon successful completion, these functions return the converted value. If no 216 conversion could be performed, \fB0\fR is returned. 217 .sp 218 .LP 219 If the correct value is outside the range of representable values, 220 \fB\(+-HUGE_VAL\fR, \fB\(+-HUGE_VALF\fR, or \fB\(+-HUGE_VALL\fR is returned 221 (according to the sign of the value), a floating point overflow exception is 222 raised, and \fBerrno\fR is set to \fBERANGE\fR. 223 .sp 224 .LP 225 If the correct value would cause an underflow, the correctly rounded result 226 (which may be normal, subnormal, or zero) is returned, a floating point 227 underflow exception is raised, and \fBerrno\fR is set to \fBERANGE\fR. 228 .SH ERRORS 229 The \fBwcstod()\fR and \fBwstod()\fR functions will fail if: 230 .sp 231 .ne 2 232 .na 233 \fBERANGE\fR 234 .ad 235 .RS 10n 236 The value to be returned would cause overflow or underflow. 237 .RE 238 239 .sp 240 .LP 241 The \fBwcstod()\fR and \fBwcstod()\fR functions may fail if: 242 .sp 243 .ne 2 244 .na 245 \fBEINVAL\fR 246 .ad 247 .RS 10n 248 No conversion could be performed. 249 .RE 250 251 .SH USAGE 252 Because 0 is returned on error and is also a valid return on success, an 253 application wishing to check for error situations should set \fBerrno\fR to 0 254 call \fBwcstod()\fR, \fBwcstof()\fR, \fBwcstold()\fR, or \fBwstod()\fR, then 255 check \fBerrno\fR and if it is non-zero, assume an error has occurred. 256 .SH ATTRIBUTES 257 See \fBattributes\fR(5) for descriptions of the following attributes: 258 .sp 259 260 .sp 261 .TS 262 box; 263 l | l 264 l | l . 265 ATTRIBUTE TYPE ATTRIBUTE VALUE 266 _ 267 Interface Stability T{ 268 \fBwcstod()\fR, \fBwcstof()\fR, and \fBwcstold()\fR are Standard. 269 T} 270 _ 271 MT-Level MT-Safe 272 .TE 273 274 .SH SEE ALSO 275 \fBiswspace\fR(3C), \fBlocaleconv\fR(3C), \fBscanf\fR(3C), \fBsetlocale\fR(3C), 276 \fBwcstol\fR(3C), \fBattributes\fR(5), \fBstandards\fR(5)