1STRTOL(3P)                 POSIX Programmer's Manual                STRTOL(3P)
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PROLOG

6       This  manual  page is part of the POSIX Programmer's Manual.  The Linux
7       implementation of this interface may differ (consult the  corresponding
8       Linux  manual page for details of Linux behavior), or the interface may
9       not be implemented on Linux.
10

NAME

12       strtol, strtoll — convert a string to a long integer
13

SYNOPSIS

15       #include <stdlib.h>
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17       long strtol(const char *restrict nptr, char **restrict endptr, int base);
18       long long strtoll(const char *restrict nptr, char **restrict endptr,
19           int base)
20

DESCRIPTION

22       The functionality described on this reference page is aligned with  the
23       ISO C  standard.  Any  conflict between the requirements described here
24       and the ISO C standard is unintentional. This  volume  of  POSIX.1‐2017
25       defers to the ISO C standard.
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27       These functions shall convert the initial portion of the string pointed
28       to by nptr to a type long and long long  representation,  respectively.
29       First, they decompose the input string into three parts:
30
31        1. An  initial, possibly empty, sequence of white-space characters (as
32           specified by isspace())
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34        2. A subject sequence interpreted as an integer  represented  in  some
35           radix determined by the value of base
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37        3. A  final  string  of one or more unrecognized characters, including
38           the terminating NUL character of the input string.
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40       Then they shall attempt to convert the subject sequence to an  integer,
41       and return the result.
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43       If the value of base is 0, the expected form of the subject sequence is
44       that of a decimal constant, octal constant,  or  hexadecimal  constant,
45       any  of  which may be preceded by a '+' or '-' sign. A decimal constant
46       begins with a non-zero digit, and consists of  a  sequence  of  decimal
47       digits.  An  octal  constant consists of the prefix '0' optionally fol‐
48       lowed by a sequence of the digits '0' to '7' only. A  hexadecimal  con‐
49       stant  consists  of  the  prefix 0x or 0X followed by a sequence of the
50       decimal digits and letters 'a' (or 'A') to 'f' (or 'F') with values  10
51       to 15 respectively.
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53       If the value of base is between 2 and 36, the expected form of the sub‐
54       ject sequence is a sequence of letters and digits representing an inte‐
55       ger  with  the radix specified by base, optionally preceded by a '+' or
56       '-' sign. The letters from 'a' (or 'A') to 'z' (or 'Z')  inclusive  are
57       ascribed  the  values  10 to 35; only letters whose ascribed values are
58       less than that of base are permitted. If the value of base is  16,  the
59       characters  0x or 0X may optionally precede the sequence of letters and
60       digits, following the sign if present.
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62       The subject sequence is defined as the longest initial  subsequence  of
63       the  input  string,  starting  with the first non-white-space character
64       that is of the expected form. The subject  sequence  shall  contain  no
65       characters  if the input string is empty or consists entirely of white-
66       space characters, or if the first non-white-space  character  is  other
67       than a sign or a permissible letter or digit.
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69       If  the subject sequence has the expected form and the value of base is
70       0, the sequence of characters starting with the first  digit  shall  be
71       interpreted  as  an  integer  constant. If the subject sequence has the
72       expected form and the value of base is between 2 and 36,  it  shall  be
73       used  as the base for conversion, ascribing to each letter its value as
74       given above. If the subject sequence begins with a <hyphen-minus>,  the
75       value  resulting from the conversion shall be negated. A pointer to the
76       final string shall be stored in the object pointed to by  endptr,  pro‐
77       vided that endptr is not a null pointer.
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79       In other than the C or POSIX locale, additional locale-specific subject
80       sequence forms may be accepted.
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82       If the subject sequence is empty or does not have the expected form, no
83       conversion  is  performed;  the  value  of  nptr shall be stored in the
84       object pointed to by  endptr,  provided  that  endptr  is  not  a  null
85       pointer.
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87       These functions shall not change the setting of errno if successful.
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89       Since  0,  {LONG_MIN} or {LLONG_MIN}, and {LONG_MAX} or {LLONG_MAX} are
90       returned on error and are also valid returns on success, an application
91       wishing  to check for error situations should set errno to 0, then call
92       strtol() or strtoll(), then check errno.
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RETURN VALUE

95       Upon successful completion, these functions shall return the  converted
96       value, if any. If no conversion could be performed, 0 shall be returned
97       and errno may be set to [EINVAL].
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99       If the value of base is not supported, 0 shall be  returned  and  errno
100       shall be set to [EINVAL].
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102       If  the  correct  value  is  outside the range of representable values,
103       {LONG_MIN}, {LONG_MAX}, {LLONG_MIN}, or {LLONG_MAX} shall  be  returned
104       (according to the sign of the value), and errno set to [ERANGE].
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ERRORS

107       These functions shall fail if:
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109       EINVAL The value of base is not supported.
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111       ERANGE The value to be returned is not representable.
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113       These functions may fail if:
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115       EINVAL No conversion could be performed.
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117       The following sections are informative.
118

EXAMPLES

120       None.
121

APPLICATION USAGE

123       Since  the  value of *endptr is unspecified if the value of base is not
124       supported, applications should either ensure that base has a  supported
125       value (0 or between 2 and 36) before the call, or check for an [EINVAL]
126       error before examining *endptr.
127

RATIONALE

129       None.
130

FUTURE DIRECTIONS

132       None.
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SEE ALSO

135       fscanf(), isalpha(), strtod()
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137       The Base Definitions volume of POSIX.1‐2017, <stdlib.h>
138
140       Portions of this text are reprinted and reproduced in  electronic  form
141       from  IEEE Std 1003.1-2017, Standard for Information Technology -- Por‐
142       table Operating System Interface (POSIX), The Open Group Base  Specifi‐
143       cations  Issue  7, 2018 Edition, Copyright (C) 2018 by the Institute of
144       Electrical and Electronics Engineers, Inc and The Open Group.   In  the
145       event of any discrepancy between this version and the original IEEE and
146       The Open Group Standard, the original IEEE and The Open Group  Standard
147       is  the  referee document. The original Standard can be obtained online
148       at http://www.opengroup.org/unix/online.html .
149
150       Any typographical or formatting errors that appear  in  this  page  are
151       most likely to have been introduced during the conversion of the source
152       files to man page format. To report such errors,  see  https://www.ker
153       nel.org/doc/man-pages/reporting_bugs.html .
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157IEEE/The Open Group                  2017                           STRTOL(3P)
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