1STRTOUL(P) POSIX Programmer's Manual STRTOUL(P)
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6 strtoul, strtoull - convert a string to an unsigned long
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9 #include <stdlib.h>
10 unsigned long strtoul(const char *restrict str,
12 char **restrict endptr, int base);
13 unsigned long long strtoull(const char *restrict str,
14 char **restrict endptr, int base);
15
18 These functions shall convert the initial portion of the string pointed
19 to by str to a type unsigned long and unsigned long long representa‐
20 tion, respectively. First, they decompose the input string into three
21 parts:
22 1. An initial, possibly empty, sequence of white-space characters (as
24 specified by isspace())
25 2. A subject sequence interpreted as an integer represented in some
27 radix determined by the value of base
28 3. A final string of one or more unrecognized characters, including
30 the terminating null byte of the input string
31 Then they shall attempt to convert the subject sequence to an unsigned
33 integer, and return the result.
34 If the value of base is 0, the expected form of the subject sequence is
36 that of a decimal constant, octal constant, or hexadecimal constant,
37 any of which may be preceded by a '+' or '-' sign. A decimal constant
38 begins with a non-zero digit, and consists of a sequence of decimal
39 digits. An octal constant consists of the prefix '0' optionally fol‐
40 lowed by a sequence of the digits '0' to '7' only. A hexadecimal con‐
41 stant consists of the prefix 0x or 0X followed by a sequence of the
42 decimal digits and letters 'a' (or 'A' ) to 'f' (or 'F' ) with values
43 10 to 15 respectively.
44 If the value of base is between 2 and 36, the expected form of the sub‐
46 ject sequence is a sequence of letters and digits representing an inte‐
47 ger with the radix specified by base, optionally preceded by a '+' or
48 '-' sign. The letters from 'a' (or 'A' ) to 'z' (or 'Z' ) inclusive are
49 ascribed the values 10 to 35; only letters whose ascribed values are
50 less than that of base are permitted. If the value of base is 16, the
51 characters 0x or 0X may optionally precede the sequence of letters and
52 digits, following the sign if present.
53 The subject sequence is defined as the longest initial subsequence of
55 the input string, starting with the first non-white-space character
56 that is of the expected form. The subject sequence shall contain no
57 characters if the input string is empty or consists entirely of white-
58 space characters, or if the first non-white-space character is other
59 than a sign or a permissible letter or digit.
60 If the subject sequence has the expected form and the value of base is
62 0, the sequence of characters starting with the first digit shall be
63 interpreted as an integer constant. If the subject sequence has the
64 expected form and the value of base is between 2 and 36, it shall be
65 used as the base for conversion, ascribing to each letter its value as
66 given above. If the subject sequence begins with a minus sign, the
67 value resulting from the conversion shall be negated. A pointer to the
68 final string shall be stored in the object pointed to by endptr, pro‐
69 vided that endptr is not a null pointer.
70 In other than the C or POSIX locales, other implementation-defined
72 subject sequences may be accepted.
73 If the subject sequence is empty or does not have the expected form, no
75 conversion shall be performed; the value of str shall be stored in the
76 object pointed to by endptr, provided that endptr is not a null
77 pointer.
78 The strtoul() function shall not change the setting of errno if suc‐
80 cessful.
81 Since 0, {ULONG_MAX}, and {ULLONG_MAX} are returned on error and are
83 also valid returns on success, an application wishing to check for
84 error situations should set errno to 0, then call strtoul() or str‐
85 toull(), then check errno.
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88 Upon successful completion, these functions shall return the converted
89 value, if any. If no conversion could be performed, 0 shall be returned
90 and errno may be set to [EINVAL]. If the correct value is outside the
91 range of representable values, {ULONG_MAX} or {ULLONG_MAX} shall be
92 returned and errno set to [ERANGE].
93
95 These functions shall fail if:
96 EINVAL The value of base is not supported.
98 ERANGE The value to be returned is not representable.
100 These functions may fail if:
103 EINVAL No conversion could be performed.
105 The following sections are informative.
108
110 None.
111
113 None.
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116 None.
117
119 None.
120
122 isalpha() , scanf() , strtod() , strtol() , the Base Definitions volume
123 of IEEE Std 1003.1-2001, <stdlib.h>
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126 Portions of this text are reprinted and reproduced in electronic form
127 from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
128 -- Portable Operating System Interface (POSIX), The Open Group Base
129 Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
130 Electrical and Electronics Engineers, Inc and The Open Group. In the
131 event of any discrepancy between this version and the original IEEE and
132 The Open Group Standard, the original IEEE and The Open Group Standard
133 is the referee document. The original Standard can be obtained online
134 at http://www.opengroup.org/unix/online.html .
135IEEE/The Open Group 2003 STRTOUL(P)