1STRTOUL(3P) POSIX Programmer's Manual STRTOUL(3P)
2
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
12 strtoul, strtoull - convert a string to an unsigned long
13
15 #include <stdlib.h>
16 unsigned long strtoul(const char *restrict str,
18 char **restrict endptr, int base);
19 unsigned long long strtoull(const char *restrict str,
20 char **restrict endptr, int base);
21
24 These functions shall convert the initial portion of the string pointed
25 to by str to a type unsigned long and unsigned long long representa‐
26 tion, respectively. First, they decompose the input string into three
27 parts:
28 1. An initial, possibly empty, sequence of white-space characters (as
30 specified by isspace())
31 2. A subject sequence interpreted as an integer represented in some
33 radix determined by the value of base
34 3. A final string of one or more unrecognized characters, including
36 the terminating null byte of the input string
37 Then they shall attempt to convert the subject sequence to an unsigned
39 integer, and return the result.
40 If the value of base is 0, the expected form of the subject sequence is
42 that of a decimal constant, octal constant, or hexadecimal constant,
43 any of which may be preceded by a '+' or '-' sign. A decimal constant
44 begins with a non-zero digit, and consists of a sequence of decimal
45 digits. An octal constant consists of the prefix '0' optionally fol‐
46 lowed by a sequence of the digits '0' to '7' only. A hexadecimal con‐
47 stant consists of the prefix 0x or 0X followed by a sequence of the
48 decimal digits and letters 'a' (or 'A' ) to 'f' (or 'F' ) with values
49 10 to 15 respectively.
50 If the value of base is between 2 and 36, the expected form of the sub‐
52 ject sequence is a sequence of letters and digits representing an inte‐
53 ger with the radix specified by base, optionally preceded by a '+' or
54 '-' sign. The letters from 'a' (or 'A' ) to 'z' (or 'Z' ) inclusive are
55 ascribed the values 10 to 35; only letters whose ascribed values are
56 less than that of base are permitted. If the value of base is 16, the
57 characters 0x or 0X may optionally precede the sequence of letters and
58 digits, following the sign if present.
59 The subject sequence is defined as the longest initial subsequence of
61 the input string, starting with the first non-white-space character
62 that is of the expected form. The subject sequence shall contain no
63 characters if the input string is empty or consists entirely of white-
64 space characters, or if the first non-white-space character is other
65 than a sign or a permissible letter or digit.
66 If the subject sequence has the expected form and the value of base is
68 0, the sequence of characters starting with the first digit shall be
69 interpreted as an integer constant. If the subject sequence has the
70 expected form and the value of base is between 2 and 36, it shall be
71 used as the base for conversion, ascribing to each letter its value as
72 given above. If the subject sequence begins with a minus sign, the
73 value resulting from the conversion shall be negated. A pointer to the
74 final string shall be stored in the object pointed to by endptr, pro‐
75 vided that endptr is not a null pointer.
76 In other than the C or POSIX locales, other implementation-defined
78 subject sequences may be accepted.
79 If the subject sequence is empty or does not have the expected form, no
81 conversion shall be performed; the value of str shall be stored in the
82 object pointed to by endptr, provided that endptr is not a null
83 pointer.
84 The strtoul() function shall not change the setting of errno if suc‐
86 cessful.
87 Since 0, {ULONG_MAX}, and {ULLONG_MAX} are returned on error and are
89 also valid returns on success, an application wishing to check for
90 error situations should set errno to 0, then call strtoul() or str‐
91 toull(), then check errno.
92
94 Upon successful completion, these functions shall return the converted
95 value, if any. If no conversion could be performed, 0 shall be returned
96 and errno may be set to [EINVAL]. If the correct value is outside the
97 range of representable values, {ULONG_MAX} or {ULLONG_MAX} shall be
98 returned and errno set to [ERANGE].
99
101 These functions shall fail if:
102 EINVAL The value of base is not supported.
104 ERANGE The value to be returned is not representable.
106 These functions may fail if:
109 EINVAL No conversion could be performed.
111 The following sections are informative.
114
116 None.
117
119 None.
120
122 None.
123
125 None.
126
128 isalpha(), scanf(), strtod(), strtol(), the Base Definitions volume of
129 IEEE Std 1003.1-2001, <stdlib.h>
130
132 Portions of this text are reprinted and reproduced in electronic form
133 from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
134 -- Portable Operating System Interface (POSIX), The Open Group Base
135 Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
136 Electrical and Electronics Engineers, Inc and The Open Group. In the
137 event of any discrepancy between this version and the original IEEE and
138 The Open Group Standard, the original IEEE and The Open Group Standard
139 is the referee document. The original Standard can be obtained online
140 at http://www.opengroup.org/unix/online.html .
141IEEE/The Open Group 2003 STRTOUL(3P)