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1 | .\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk) |
2 | .\" | |
93015253 | 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14 | .\" manual page may be incorrect or out-of-date.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 Sun Jul 25 10:53:39 1993 by Rik Faith (faith@cs.unc.edu) | |
30 | .\" Added correction due to nsd@bbc.com (Nick Duffek) - aeb, 950610 | |
9ba01802 | 31 | .TH STRTOL 3 2019-03-06 "GNU" "Linux Programmer's Manual" |
fea681da MK |
32 | .SH NAME |
33 | strtol, strtoll, strtoq \- convert a string to a long integer | |
34 | .SH SYNOPSIS | |
35 | .nf | |
36 | .B #include <stdlib.h> | |
68e4db0a | 37 | .PP |
62218dc0 | 38 | .BI "long int strtol(const char *" nptr ", char **" endptr ", int " base ); |
68e4db0a | 39 | .PP |
62218dc0 MK |
40 | .BI "long long int strtoll(const char *" nptr ", char **" endptr \ |
41 | ", int " base ); | |
fea681da | 42 | .fi |
68e4db0a | 43 | .PP |
cc4615cc MK |
44 | .in -4n |
45 | Feature Test Macro Requirements for glibc (see | |
46 | .BR feature_test_macros (7)): | |
47 | .in | |
68e4db0a | 48 | .PP |
cc4615cc MK |
49 | .ad l |
50 | .BR strtoll (): | |
e0a98111 | 51 | .RS 4 |
2b1b0424 MK |
52 | _ISOC99_SOURCE |
53 | || /* Glibc versions <= 2.19: */ _SVID_SOURCE || _BSD_SOURCE | |
e0a98111 MK |
54 | .RE |
55 | .ad | |
fea681da | 56 | .SH DESCRIPTION |
60a90ecd MK |
57 | The |
58 | .BR strtol () | |
59 | function converts the initial part of the string | |
46d8df8e MK |
60 | in |
61 | .I nptr | |
62 | to a long integer value according to the given | |
63 | .IR base , | |
fea681da MK |
64 | which must be between 2 and 36 inclusive, or be the special value 0. |
65 | .PP | |
3f266a43 | 66 | The string may begin with an arbitrary amount of white space (as |
fea681da MK |
67 | determined by |
68 | .BR isspace (3)) | |
f81fb444 | 69 | followed by a single optional \(aq+\(aq or \(aq\-\(aq sign. |
46d8df8e MK |
70 | If |
71 | .I base | |
72 | is zero or 16, the string may then include a | |
e5b5658c | 73 | "0x" or "0X" prefix, and the number will be read in base 16; otherwise, a |
46d8df8e MK |
74 | zero |
75 | .I base | |
76 | is taken as 10 (decimal) unless the next character | |
f81fb444 | 77 | is \(aq0\(aq, in which case it is taken as 8 (octal). |
fea681da | 78 | .PP |
c13182ef | 79 | The remainder of the string is converted to a |
fefe023e MK |
80 | .I long int |
81 | value | |
fea681da | 82 | in the obvious manner, stopping at the first character which is not a |
c13182ef | 83 | valid digit in the given base. |
f81fb444 | 84 | (In bases above 10, the letter \(aqA\(aq in |
efaef3da | 85 | either uppercase or lowercase represents 10, \(aqB\(aq represents 11, and so |
f81fb444 | 86 | forth, with \(aqZ\(aq representing 35.) |
fea681da | 87 | .PP |
46d8df8e MK |
88 | If |
89 | .I endptr | |
90 | is not NULL, | |
60a90ecd MK |
91 | .BR strtol () |
92 | stores the address of the | |
46d8df8e MK |
93 | first invalid character in |
94 | .IR *endptr . | |
c13182ef | 95 | If there were no digits at |
60a90ecd MK |
96 | all, |
97 | .BR strtol () | |
46d8df8e MK |
98 | stores the original value of |
99 | .I nptr | |
100 | in | |
101 | .I *endptr | |
102 | (and returns 0). | |
103 | In particular, if | |
104 | .I *nptr | |
d1a71985 | 105 | is not \(aq\e0\(aq but |
46d8df8e | 106 | .I **endptr |
d1a71985 | 107 | is \(aq\e0\(aq on return, the entire string is valid. |
fea681da MK |
108 | .PP |
109 | The | |
63aa9df0 | 110 | .BR strtoll () |
fea681da | 111 | function works just like the |
63aa9df0 | 112 | .BR strtol () |
fea681da | 113 | function but returns a long long integer value. |
47297adb | 114 | .SH RETURN VALUE |
60a90ecd MK |
115 | The |
116 | .BR strtol () | |
117 | function returns the result of the conversion, | |
c13182ef MK |
118 | unless the value would underflow or overflow. |
119 | If an underflow occurs, | |
60a90ecd | 120 | .BR strtol () |
097585ed MK |
121 | returns |
122 | .BR LONG_MIN . | |
60a90ecd MK |
123 | If an overflow occurs, |
124 | .BR strtol () | |
097585ed MK |
125 | returns |
126 | .BR LONG_MAX . | |
46d8df8e MK |
127 | In both cases, |
128 | .I errno | |
129 | is set to | |
09b235db | 130 | .BR ERANGE . |
fea681da | 131 | Precisely the same holds for |
63aa9df0 | 132 | .BR strtoll () |
097585ed MK |
133 | (with |
134 | .B LLONG_MIN | |
135 | and | |
136 | .B LLONG_MAX | |
137 | instead of | |
138 | .B LONG_MIN | |
139 | and | |
140 | .BR LONG_MAX ). | |
fea681da MK |
141 | .SH ERRORS |
142 | .TP | |
143 | .B EINVAL | |
144 | (not in C99) | |
145 | The given | |
146 | .I base | |
147 | contains an unsupported value. | |
148 | .TP | |
149 | .B ERANGE | |
150 | The resulting value was out of range. | |
dd3568a1 | 151 | .PP |
46d8df8e | 152 | The implementation may also set |
51700fd7 | 153 | .IR errno |
46d8df8e MK |
154 | to |
155 | .B EINVAL | |
156 | in case | |
fea681da | 157 | no conversion was performed (no digits seen, and 0 returned). |
ca74032e | 158 | .SH ATTRIBUTES |
de80a16a PH |
159 | For an explanation of the terms used in this section, see |
160 | .BR attributes (7). | |
161 | .TS | |
162 | allbox; | |
163 | lbw29 lb lb | |
164 | l l l. | |
165 | Interface Attribute Value | |
166 | T{ | |
ca74032e PH |
167 | .BR strtol (), |
168 | .BR strtoll (), | |
ca74032e | 169 | .BR strtoq () |
de80a16a PH |
170 | T} Thread safety MT-Safe locale |
171 | .TE | |
47297adb | 172 | .SH CONFORMING TO |
c2fb338e MK |
173 | .BR strtol (): |
174 | POSIX.1-2001, POSIX.1-2008, C89, C99 SVr4, 4.3BSD. | |
847e0d88 | 175 | .PP |
c2fb338e MK |
176 | .BR strtoll (): |
177 | POSIX.1-2001, POSIX.1-2008, C99. | |
fea681da | 178 | .SH NOTES |
c13182ef | 179 | Since |
fefe023e | 180 | .BR strtol () |
c13182ef | 181 | can legitimately return 0, |
097585ed MK |
182 | .BR LONG_MAX , |
183 | or | |
184 | .B LONG_MIN | |
185 | .RB ( LLONG_MAX | |
186 | or | |
187 | .B LLONG_MIN | |
188 | for | |
fefe023e MK |
189 | .BR strtoll ()) |
190 | on both success and failure, the calling program should set | |
191 | .I errno | |
c13182ef | 192 | to 0 before the call, |
fefe023e MK |
193 | and then determine if an error occurred by checking whether |
194 | .I errno | |
c7094399 | 195 | has a nonzero value after the call. |
847e0d88 | 196 | .PP |
c2fb338e | 197 | According to POSIX.1, |
36127c0e | 198 | in locales other than the "C" and "POSIX", |
6bdb0096 MK |
199 | these functions may accept other, |
200 | implementation-defined numeric strings. | |
dd3568a1 | 201 | .PP |
fea681da | 202 | BSD also has |
51f5698d | 203 | .PP |
fea681da | 204 | .in +4n |
bdd915e2 | 205 | .EX |
a08ea57c | 206 | .BI "quad_t strtoq(const char *" nptr ", char **" endptr ", int " base ); |
b8302363 | 207 | .EE |
e646a1ba | 208 | .in |
b9c93deb | 209 | .PP |
fea681da MK |
210 | with completely analogous definition. |
211 | Depending on the wordsize of the current architecture, this | |
212 | may be equivalent to | |
63aa9df0 | 213 | .BR strtoll () |
fea681da | 214 | or to |
63aa9df0 | 215 | .BR strtol (). |
56aee868 MK |
216 | .SH EXAMPLE |
217 | The program shown below demonstrates the use of | |
218 | .BR strtol (). | |
76c44d83 | 219 | The first command-line argument specifies a string from which |
56aee868 MK |
220 | .BR strtol () |
221 | should parse a number. | |
c13182ef | 222 | The second (optional) argument specifies the base to be used for |
56aee868 | 223 | the conversion. |
0acd0e57 MK |
224 | (This argument is converted to numeric form using |
225 | .BR atoi (3), | |
c13182ef | 226 | a function that performs no error checking and |
0acd0e57 MK |
227 | has a simpler interface than |
228 | .BR strtol ().) | |
56aee868 | 229 | Some examples of the results produced by this program are the following: |
e646a1ba | 230 | .PP |
a08ea57c | 231 | .in +4n |
e646a1ba | 232 | .EX |
b43a3b30 | 233 | .RB "$" " ./a.out 123" |
56aee868 | 234 | strtol() returned 123 |
b43a3b30 | 235 | .RB "$" " ./a.out \(aq 123\(aq" |
56aee868 | 236 | strtol() returned 123 |
b43a3b30 | 237 | .RB "$" " ./a.out 123abc" |
56aee868 MK |
238 | strtol() returned 123 |
239 | Further characters after number: abc | |
b43a3b30 | 240 | .RB "$" " ./a.out 123abc 55" |
56aee868 | 241 | strtol: Invalid argument |
b43a3b30 | 242 | .RB "$" " ./a.out \(aq\(aq" |
56aee868 | 243 | No digits were found |
b43a3b30 | 244 | .RB "$" " ./a.out 4000000000" |
56aee868 | 245 | strtol: Numerical result out of range |
b8302363 | 246 | .EE |
a08ea57c | 247 | .in |
9c330504 | 248 | .SS Program source |
d84d0300 | 249 | \& |
e7d0bb47 | 250 | .EX |
56aee868 MK |
251 | #include <stdlib.h> |
252 | #include <limits.h> | |
253 | #include <stdio.h> | |
254 | #include <errno.h> | |
255 | ||
256 | int | |
257 | main(int argc, char *argv[]) | |
258 | { | |
259 | int base; | |
260 | char *endptr, *str; | |
261 | long val; | |
262 | ||
263 | if (argc < 2) { | |
d1a71985 | 264 | fprintf(stderr, "Usage: %s str [base]\en", argv[0]); |
56aee868 | 265 | exit(EXIT_FAILURE); |
c13182ef | 266 | } |
56aee868 MK |
267 | |
268 | str = argv[1]; | |
269 | base = (argc > 2) ? atoi(argv[2]) : 10; | |
270 | ||
271 | errno = 0; /* To distinguish success/failure after call */ | |
272 | val = strtol(str, &endptr, base); | |
273 | ||
274 | /* Check for various possible errors */ | |
275 | ||
276 | if ((errno == ERANGE && (val == LONG_MAX || val == LONG_MIN)) | |
277 | || (errno != 0 && val == 0)) { | |
278 | perror("strtol"); | |
279 | exit(EXIT_FAILURE); | |
c13182ef | 280 | } |
56aee868 MK |
281 | |
282 | if (endptr == str) { | |
d1a71985 | 283 | fprintf(stderr, "No digits were found\en"); |
56aee868 | 284 | exit(EXIT_FAILURE); |
c13182ef | 285 | } |
56aee868 | 286 | |
0acd0e57 | 287 | /* If we got here, strtol() successfully parsed a number */ |
56aee868 | 288 | |
d1a71985 | 289 | printf("strtol() returned %ld\en", val); |
56aee868 | 290 | |
d1a71985 MK |
291 | if (*endptr != \(aq\e0\(aq) /* Not necessarily an error... */ |
292 | printf("Further characters after number: %s\en", endptr); | |
56aee868 MK |
293 | |
294 | exit(EXIT_SUCCESS); | |
295 | } | |
e7d0bb47 | 296 | .EE |
47297adb | 297 | .SH SEE ALSO |
fea681da MK |
298 | .BR atof (3), |
299 | .BR atoi (3), | |
300 | .BR atol (3), | |
301 | .BR strtod (3), | |
995eea22 JW |
302 | .BR strtoul (3), |
303 | .BR strtoimax (3) |