11620 strtod man page typo equence

27 .\" The contents of this file are subject to the terms of the 28 .\" Common Development and Distribution License (the "License"). 29 .\" You may not use this file except in compliance with the License. 30 .\" 31 .\" You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 32 .\" or http://www.opensolaris.org/os/licensing. 33 .\" See the License for the specific language governing permissions 34 .\" and limitations under the License. 35 .\" 36 .\" When distributing Covered Code, include this CDDL HEADER in each 37 .\" file and include the License file at usr/src/OPENSOLARIS.LICENSE. 38 .\" If applicable, add the following below this CDDL HEADER, with the 39 .\" fields enclosed by brackets "[]" replaced with your own identifying 40 .\" information: Portions Copyright [yyyy] [name of copyright owner] 41 .\" 42 .\" 43 .\" Copyright 1989 AT&T 44 .\" Copyright (c) 1992, X/Open Company Limited. All Rights Reserved. 45 .\" Portions Copyright (c) 2006, Sun Microsystems, Inc. All Rights Reserved. 46 .\" 47 .TH STRTOD 3C "Nov 1, 2003" 48 .SH NAME 49 strtod, strtof, strtold, atof \- convert string to floating-point number 50 .SH SYNOPSIS 51 .LP 52 .nf 53 #include <stdlib.h> 54 55 \fBdouble\fR \fBstrtod\fR(\fBconst char *restrict\fR \fInptr\fR, \fBchar **restrict\fR \fIendptr\fR); 56 .fi 57 58 .LP 59 .nf 60 \fBfloat\fR \fBstrtof\fR(\fBconst char *restrict\fR \fInptr\fR, \fBchar **restrict\fR \fIendptr\fR); 61 .fi 62 63 .LP 64 .nf 65 \fBlong double\fR \fBstrtold\fR(\fBconst char *restrict\fR \fInptr\fR, \fBchar **restrict\fR \fIendptr\fR); 66 .fi 67 68 .LP 69 .nf 70 \fBdouble\fR \fBatof\fR(\fBconst char *\fR\fIstr\fR); 71 .fi 72 73 .SH DESCRIPTION 74 .sp 75 .LP 76 The \fBstrtod()\fR, \fBstrtof()\fR, and \fBstrtold()\fR functions convert the 77 initial portion of the string pointed to by \fInptr\fR to \fBdouble\fR, 78 \fBfloat\fR, and \fBlong double\fR representation, respectively. First they 79 decompose the input string into three parts: 80 .RS +4 81 .TP 82 1. 83 An initial, possibly empty, sequence of white-space characters (as specified 84 by \fBisspace\fR(3C)) 85 .RE 86 .RS +4 87 .TP 88 2. 89 A subject sequence interpreted as a floating-point constant or representing 90 infinity or NaN 91 .RE 92 .RS +4 93 .TP 94 3. 95 A final string of one or more unrecognized characters, including the ```
132 .sp
133 .in +2
134 .nf
135 n-char-sequence:
136 digit
137 nondigit
138 n-char-sequence digit
139 n-char-sequence nondigit
140 .fi
141 .in -2
142
143 .RE
144 .sp
145 .LP
146 In default mode for \fBstrtod()\fR, only decimal, INF/INFINITY, and
147 NAN/NAN(\fIn-char-sequence\fR) forms are recognized. In C99/SUSv3 mode,
148 hexadecimal strings are also recognized.
149 .sp
150 .LP
151 In default mode for \fBstrtod()\fR, the \fIn-char-sequence\fR in the
152 NAN(\fIn-char-equence\fR) form can contain any character except ')' (right
153 parenthesis) or '\e0' (null). In C99/SUSv3 mode, the \fIn-char-sequence\fR can
154 contain only upper and lower case letters, digits, and '_' (underscore).
155 .sp
156 .LP
157 The \fBstrtof()\fR and \fBstrtold()\fR functions always function in
158 C99/SUSv3-conformant mode.
159 .sp
160 .LP
161 The subject sequence is defined as the longest initial subsequence of the input
162 string, starting with the first non-white-space character, that is of the
163 expected form. The subject sequence contains no characters if the input string
164 is not of the expected form.
165 .sp
166 .LP
167 If the subject sequence has the expected form for a floating-point number, the
168 sequence of characters starting with the first digit or the decimal-point
169 character (whichever occurs first) is interpreted as a floating constant of the
170 C language, except that the radix character is used in place of a period, and
171 that if neither an exponent part nor a radix character appears in a decimal
172 floating-point number, or if a binary exponent part does not appear in a
``` 185 point inexact, underflow, or overflow exceptions as appropriate. 186 .sp 187 .LP 188 The radix character is defined in the program's locale (category 189 \fBLC_NUMERIC\fR). In the POSIX locale, or in a locale where the radix 190 character is not defined, the radix character defaults to a period ('.'). 191 .sp 192 .LP 193 If the subject sequence is empty or does not have the expected form, no 194 conversion is performed; the value of \fInptr\fR is stored in the object 195 pointed to by \fIendptr\fR, provided that \fIendptr\fR is not a null pointer. 196 .sp 197 .LP 198 The \fBstrtod()\fR function does not change the setting of \fBerrno\fR if 199 successful. 200 .sp 201 .LP 202 The \fBatof(\fR\fIstr\fR\fB)\fR function call is equivalent to 203 \fBstrtod(\fR\fInptr\fR\fB, (char **)NULL)\fR. 204 .SH RETURN VALUES 205 .sp 206 .LP 207 Upon successful completion, these functions return the converted value. If no 208 conversion could be performed, \fB0\fR is returned. 209 .sp 210 .LP 211 If the correct value is outside the range of representable values, 212 \fB\(+-HUGE_VAL\fR, \fB\(+-HUGE_VALF\fR, or \fB\(+-HUGE_VALL\fR is returned 213 (according to the sign of the value), a floating point overflow exception is 214 raised, and \fBerrno\fR is set to \fBERANGE\fR. 215 .sp 216 .LP 217 If the correct value would cause an underflow, the correctly rounded result 218 (which may be normal, subnormal, or zero) is returned, a floating point 219 underflow exception is raised, and \fBerrno\fR is set to \fBERANGE\fR. 220 .SH ERRORS 221 .sp 222 .LP 223 These functions will fail if: 224 .sp 225 .ne 2 226 .na 227 \fB\fBERANGE\fR\fR 228 .ad 229 .RS 10n 230 The value to be returned would cause overflow or underflow 231 .RE 232 233 .sp 234 .LP 235 These functions may fail if: 236 .sp 237 .ne 2 238 .na 239 \fB\fBEINVAL\fR\fR 240 .ad 241 .RS 10n 242 No conversion could be performed. 243 .RE 244 245 .SH USAGE 246 .sp 247 .LP 248 Since 0 is returned on error and is also a valid return on success, an 249 application wishing to check for error situations should set \fBerrno\fR to 0, 250 then call \fBstrtod()\fR, \fBstrtof()\fR, or \fBstrtold()\fR, then check 251 \fBerrno\fR. 252 .sp 253 .LP 254 The changes to \fBstrtod()\fR introduced by the ISO/IEC 9899: 1999 standard can 255 alter the behavior of well-formed applications complying with the ISO/IEC 9899: 256 1990 standard and thus earlier versions of IEEE Std 1003.1-200x. One such 257 example would be: 258 .sp 259 .in +2 260 .nf 261 int 262 what_kind_of_number (char *s) 263 { 264 char *endp; 265 double d; 266 long l; 267 d = strtod(s, &endp); 300 It's an integer with value 16 301 .fi 302 .in -2 303 304 .sp 305 .LP 306 With the ISO/IEC 9899: 1999 standard, the result is: 307 .sp 308 .in +2 309 .nf 310 It's a float with value 16 311 .fi 312 .in -2 313 314 .sp 315 .LP 316 The change in behavior is due to the inclusion of floating-point numbers in 317 hexadecimal notation without requiring that either a decimal point or the 318 binary exponent be present. 319 .SH ATTRIBUTES 320 .sp 321 .LP 322 See \fBattributes\fR(5) for descriptions of the following attributes: 323 .sp 324 325 .sp 326 .TS 327 box; 328 c | c 329 l | l . 330 ATTRIBUTE TYPE ATTRIBUTE VALUE 331 _ 332 CSI Enabled 333 _ 334 Interface Stability Standard 335 _ 336 MT-Level MT-Safe with exceptions 337 .TE 338 339 .SH SEE ALSO 340 .sp 341 .LP 342 \fBisspace\fR(3C), \fBlocaleconv\fR(3C), \fBscanf\fR(3C), \fBsetlocale\fR(3C), 343 \fBstrtol\fR(3C), \fBattributes\fR(5), \fBstandards\fR(5) 344 .SH NOTES 345 .sp 346 .LP 347 The \fBstrtod()\fR and \fBatof()\fR functions can be used safely in 348 multithreaded applications, as long as \fBsetlocale\fR(3C) is not called to 349 change the locale. 350 .sp 351 .LP 352 The DESCRIPTION and RETURN VALUES sections above are very similar to the 353 wording used by the Single UNIX Specification version 2 (SUSv2) and the 1989 C 354 Standard to describe the behavior of the \fBstrtod()\fR function. Since some 355 users have reported that they find the description confusing, the following 356 notes might be helpful. 357 .RS +4 358 .TP 359 1. 360 The \fBstrtod()\fR function does not modify the string pointed to by 361 \fIstr\fR and does not \fBmalloc()\fR space to hold the decomposed portions of 362 the input string. 363 .RE 364 .RS +4 365 .TP 366 2. | ```
27 .\" The contents of this file are subject to the terms of the
28 .\" Common Development and Distribution License (the "License").
29 .\" You may not use this file except in compliance with the License.
30 .\"
31 .\" You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
32 .\" or http://www.opensolaris.org/os/licensing.
33 .\" See the License for the specific language governing permissions
34 .\" and limitations under the License.
35 .\"
36 .\" When distributing Covered Code, include this CDDL HEADER in each
37 .\" file and include the License file at usr/src/OPENSOLARIS.LICENSE.
38 .\" If applicable, add the following below this CDDL HEADER, with the
39 .\" fields enclosed by brackets "[]" replaced with your own identifying
40 .\" information: Portions Copyright [yyyy] [name of copyright owner]
41 .\"
42 .\"
43 .\" Copyright 1989 AT&T
44 .\" Copyright (c) 1992, X/Open Company Limited. All Rights Reserved.
45 .\" Portions Copyright (c) 2006, Sun Microsystems, Inc. All Rights Reserved.
46 .\"
47 .TH STRTOD 3C "Aug 25, 2019"
48 .SH NAME
49 strtod, strtof, strtold, atof \- convert string to floating-point number
50 .SH SYNOPSIS
51 .nf
52 #include <stdlib.h>
53
54 \fBdouble\fR \fBstrtod\fR(\fBconst char *restrict\fR \fInptr\fR, \fBchar **restrict\fR \fIendptr\fR);
55 .fi
56
57 .LP
58 .nf
59 \fBfloat\fR \fBstrtof\fR(\fBconst char *restrict\fR \fInptr\fR, \fBchar **restrict\fR \fIendptr\fR);
60 .fi
61
62 .LP
63 .nf
64 \fBlong double\fR \fBstrtold\fR(\fBconst char *restrict\fR \fInptr\fR, \fBchar **restrict\fR \fIendptr\fR);
65 .fi
66
67 .LP
68 .nf
69 \fBdouble\fR \fBatof\fR(\fBconst char *\fR\fIstr\fR);
70 .fi
71
72 .SH DESCRIPTION
73 The \fBstrtod()\fR, \fBstrtof()\fR, and \fBstrtold()\fR functions convert the
74 initial portion of the string pointed to by \fInptr\fR to \fBdouble\fR,
75 \fBfloat\fR, and \fBlong double\fR representation, respectively. First they
76 decompose the input string into three parts:
77 .RS +4
78 .TP
79 1.
80 An initial, possibly empty, sequence of white-space characters (as specified
81 by \fBisspace\fR(3C))
82 .RE
83 .RS +4
84 .TP
85 2.
86 A subject sequence interpreted as a floating-point constant or representing
87 infinity or NaN
88 .RE
89 .RS +4
90 .TP
91 3.
92 A final string of one or more unrecognized characters, including the
``` ```
129 .sp
130 .in +2
131 .nf
132 n-char-sequence:
133 digit
134 nondigit
135 n-char-sequence digit
136 n-char-sequence nondigit
137 .fi
138 .in -2
139
140 .RE
141 .sp
142 .LP
143 In default mode for \fBstrtod()\fR, only decimal, INF/INFINITY, and
144 NAN/NAN(\fIn-char-sequence\fR) forms are recognized. In C99/SUSv3 mode,
145 hexadecimal strings are also recognized.
146 .sp
147 .LP
148 In default mode for \fBstrtod()\fR, the \fIn-char-sequence\fR in the
149 NAN(\fIn-char-sequence\fR) form can contain any character except ')' (right
150 parenthesis) or '\e0' (null). In C99/SUSv3 mode, the \fIn-char-sequence\fR can
151 contain only upper and lower case letters, digits, and '_' (underscore).
152 .sp
153 .LP
154 The \fBstrtof()\fR and \fBstrtold()\fR functions always function in
155 C99/SUSv3-conformant mode.
156 .sp
157 .LP
158 The subject sequence is defined as the longest initial subsequence of the input
159 string, starting with the first non-white-space character, that is of the
160 expected form. The subject sequence contains no characters if the input string
161 is not of the expected form.
162 .sp
163 .LP
164 If the subject sequence has the expected form for a floating-point number, the
165 sequence of characters starting with the first digit or the decimal-point
166 character (whichever occurs first) is interpreted as a floating constant of the
167 C language, except that the radix character is used in place of a period, and
168 that if neither an exponent part nor a radix character appears in a decimal
169 floating-point number, or if a binary exponent part does not appear in a
``` 182 point inexact, underflow, or overflow exceptions as appropriate. 183 .sp 184 .LP 185 The radix character is defined in the program's locale (category 186 \fBLC_NUMERIC\fR). In the POSIX locale, or in a locale where the radix 187 character is not defined, the radix character defaults to a period ('.'). 188 .sp 189 .LP 190 If the subject sequence is empty or does not have the expected form, no 191 conversion is performed; the value of \fInptr\fR is stored in the object 192 pointed to by \fIendptr\fR, provided that \fIendptr\fR is not a null pointer. 193 .sp 194 .LP 195 The \fBstrtod()\fR function does not change the setting of \fBerrno\fR if 196 successful. 197 .sp 198 .LP 199 The \fBatof(\fR\fIstr\fR\fB)\fR function call is equivalent to 200 \fBstrtod(\fR\fInptr\fR\fB, (char **)NULL)\fR. 201 .SH RETURN VALUES 202 Upon successful completion, these functions return the converted value. If no 203 conversion could be performed, \fB0\fR is returned. 204 .sp 205 .LP 206 If the correct value is outside the range of representable values, 207 \fB\(+-HUGE_VAL\fR, \fB\(+-HUGE_VALF\fR, or \fB\(+-HUGE_VALL\fR is returned 208 (according to the sign of the value), a floating point overflow exception is 209 raised, and \fBerrno\fR is set to \fBERANGE\fR. 210 .sp 211 .LP 212 If the correct value would cause an underflow, the correctly rounded result 213 (which may be normal, subnormal, or zero) is returned, a floating point 214 underflow exception is raised, and \fBerrno\fR is set to \fBERANGE\fR. 215 .SH ERRORS 216 These functions will fail if: 217 .sp 218 .ne 2 219 .na 220 \fBERANGE\fR 221 .ad 222 .RS 10n 223 The value to be returned would cause overflow or underflow 224 .RE 225 226 .sp 227 .LP 228 These functions may fail if: 229 .sp 230 .ne 2 231 .na 232 \fBEINVAL\fR 233 .ad 234 .RS 10n 235 No conversion could be performed. 236 .RE 237 238 .SH USAGE 239 Since 0 is returned on error and is also a valid return on success, an 240 application wishing to check for error situations should set \fBerrno\fR to 0, 241 then call \fBstrtod()\fR, \fBstrtof()\fR, or \fBstrtold()\fR, then check 242 \fBerrno\fR. 243 .sp 244 .LP 245 The changes to \fBstrtod()\fR introduced by the ISO/IEC 9899: 1999 standard can 246 alter the behavior of well-formed applications complying with the ISO/IEC 9899: 247 1990 standard and thus earlier versions of IEEE Std 1003.1-200x. One such 248 example would be: 249 .sp 250 .in +2 251 .nf 252 int 253 what_kind_of_number (char *s) 254 { 255 char *endp; 256 double d; 257 long l; 258 d = strtod(s, &endp); 291 It's an integer with value 16 292 .fi 293 .in -2 294 295 .sp 296 .LP 297 With the ISO/IEC 9899: 1999 standard, the result is: 298 .sp 299 .in +2 300 .nf 301 It's a float with value 16 302 .fi 303 .in -2 304 305 .sp 306 .LP 307 The change in behavior is due to the inclusion of floating-point numbers in 308 hexadecimal notation without requiring that either a decimal point or the 309 binary exponent be present. 310 .SH ATTRIBUTES 311 See \fBattributes\fR(5) for descriptions of the following attributes: 312 .sp 313 314 .sp 315 .TS 316 box; 317 c | c 318 l | l . 319 ATTRIBUTE TYPE ATTRIBUTE VALUE 320 _ 321 CSI Enabled 322 _ 323 Interface Stability Standard 324 _ 325 MT-Level MT-Safe with exceptions 326 .TE 327 328 .SH SEE ALSO 329 \fBisspace\fR(3C), \fBlocaleconv\fR(3C), \fBscanf\fR(3C), \fBsetlocale\fR(3C), 330 \fBstrtol\fR(3C), \fBattributes\fR(5), \fBstandards\fR(5) 331 .SH NOTES 332 The \fBstrtod()\fR and \fBatof()\fR functions can be used safely in 333 multithreaded applications, as long as \fBsetlocale\fR(3C) is not called to 334 change the locale. 335 .sp 336 .LP 337 The DESCRIPTION and RETURN VALUES sections above are very similar to the 338 wording used by the Single UNIX Specification version 2 (SUSv2) and the 1989 C 339 Standard to describe the behavior of the \fBstrtod()\fR function. Since some 340 users have reported that they find the description confusing, the following 341 notes might be helpful. 342 .RS +4 343 .TP 344 1. 345 The \fBstrtod()\fR function does not modify the string pointed to by 346 \fIstr\fR and does not \fBmalloc()\fR space to hold the decomposed portions of 347 the input string. 348 .RE 349 .RS +4 350 .TP 351 2. |