1strtol(3C) Standard C Library Functions strtol(3C)
2
6 strtol, strtoll, atol, atoll, atoi, lltostr, ulltostr - string conver‐
7 sion routines
8
10 #include <stdlib.h>
11 long strtol(const char *restrict str, char **restrict endptr, int base);
13 long long strtoll(const char *restrict str, char **restrict endptr,
16 int base);
17 long atol(const char *str);
20 long long atoll(const char *str);
23 int atoi(const char *str);
26 char *lltostr(long long value, char *endptr);
29 char *ulltostr(unsigned long long value, char *endptr);
32
35 strtol() and strtoll()
36 The strtol() function converts the initial portion of the string
37 pointed to by str to a type long int representation.
38 The strtoll() function converts the initial portion of the string
41 pointed to by str to a type long long representation.
42 Both functions first decompose the input string into three parts: an
45 initial, possibly empty, sequence of white-space characters (as speci‐
46 fied by isspace(3C)); a subject sequence interpreted as an integer rep‐
47 resented in some radix determined by the value of base; and a final
48 string of one or more unrecognized characters, including the terminat‐
49 ing null byte of the input string. They then attempt to convert the
50 subject sequence to an integer and return the result.
51 If the value of base is 0, the expected form of the subject sequence is
54 that of a decimal constant, octal constant or hexadecimal constant, any
55 of which may be preceded by a + or − sign. A decimal constant begins
56 with a non-zero digit, and consists of a sequence of decimal digits. An
57 octal constant consists of the prefix 0 optionally followed by a
58 sequence of the digits 0 to 7 only. A hexadecimal constant consists of
59 the prefix 0x or 0X followed by a sequence of the decimal digits and
60 letters a (or A) to f (or F) with values 10 to 15 respectively.
61 If the value of base is between 2 and 36, the expected form of the sub‐
64 ject sequence is a sequence of letters and digits representing an inte‐
65 ger with the radix specified by base, optionally preceded by a + or −
66 sign. The letters from a (or A) to z (or Z) inclusive are ascribed the
67 values 10 to 35; only letters whose ascribed values are less than that
68 of base are permitted. If the value of base is 16, the characters 0x or
69 0X may optionally precede the sequence of letters and digits, following
70 the sign if present.
71 The subject sequence is defined as the longest initial subsequence of
74 the input string, starting with the first non-white-space character,
75 that is of the expected form. The subject sequence contains no charac‐
76 ters if the input string is empty or consists entirely of white-space
77 characters, or if the first non-white-space character is other than a
78 sign or a permissible letter or digit.
79 If the subject sequence has the expected form and the value of base is
82 0, the sequence of characters starting with the first digit is inter‐
83 preted as an integer constant. If the subject sequence has the expected
84 form and the value of base is between 2 and 36, it is used as the base
85 for conversion, ascribing to each letter its value as given above. If
86 the subject sequence begins with a minus sign, the value resulting from
87 the conversion is negated. A pointer to the final string is stored in
88 the object pointed to by endptr, provided that endptr is not a null
89 pointer.
90 In other than the POSIX locale, additional implementation-dependent
93 subject sequence forms may be accepted.
94 If the subject sequence is empty or does not have the expected form, no
97 conversion is performed; the value of str is stored in the object
98 pointed to by endptr, provided that endptr is not a null pointer.
99 atol(), atoll() and atoi()
101 Except for behavior on error, atol() is equivalent to: strtol(str,
102 (char **)NULL, 10).
103 Except for behavior on error, atoll() is equivalent to: strtoll(str,
106 (char **)NULL, 10).
107 Except for behavior on error, atoi() is equivalent to: (int) str‐
110 tol(str, (char **)NULL, 10).
111 If the value cannot be represented, the behavior is undefined.
114 lltostr() and ulltostr()
116 The lltostr() function returns a pointer to the string represented by
117 the long long value. The endptr argument is assumed to point to the
118 byte following a storage area into which the decimal representation of
119 value is to be placed as a string. The lltostr() function converts
120 value to decimal and produces the string, and returns a pointer to the
121 beginning of the string. No leading zeros are produced, and no termi‐
122 nating null is produced. The low-order digit of the result always occu‐
123 pies memory position endptr−1. The behavior of lltostr() is undefined
124 if value is negative. A single zero digit is produced if value is 0.
125 The ulltostr() function is similar to lltostr() except that value is an
128 unsigned long long.
129
131 Upon successful completion, strtol(), strtoll(), atol(), atoll(), and
132 atoi() return the converted value, if any. If no conversion could be
133 performed, strtol() and strtoll() return 0 and errno may be set to EIN‐
134 VAL.
135 If the correct value is outside the range of representable values, str‐
138 tol() returns LONG_MAX or LONG_MIN and strtoll() returns LLONG_MAX or
139 LLONG_MIN (according to the sign of the value), and errno is set to
140 ERANGE.
141 Upon successful completion, lltostr() and ulltostr() return a pointer
144 to the converted string.
145
147 The strtol() and strtoll() functions will fail if:
148 ERANGE The value to be returned is not representable. The strtol()
150 and strtoll() functions may fail if:
151 EINVAL The value of base is not supported.
154
157 Because 0, LONG_MIN, LONG_MAX, LLONG_MIN, and LLONG_MAX are returned on
158 error and are also valid returns on success, an application wishing to
159 check for error situations should set errno to 0, call the function,
160 then check errno and if it is non-zero, assume an error has occurred.
161 The strtol() function no longer accepts values greater than LONG_MAX or
164 LLONG_MAX as valid input. Use strtoul(3C) instead.
165 Calls to atoi() and atol() might be faster than corresponding calls to
168 strtol(), and calls to atoll() might be faster than corresponding calls
169 to strtoll(). However, applications should not use the atoi(), atol(),
170 or atoll() functions unless they know the value represented by the
171 argument will be in range for the corresponding result type.
172
174 See attributes(5) for descriptions of the following attributes:
175 ┌─────────────────────────────┬─────────────────────────────┐
180 │ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
181 ├─────────────────────────────┼─────────────────────────────┤
182 │Interface Stability │See below. │
183 ├─────────────────────────────┼─────────────────────────────┤
184 │MT-Level │MT-Safe │
185 └─────────────────────────────┴─────────────────────────────┘
186 The strtol(), strtoll(), atol(), atoll(), and atoi() functions are
189 Standard.
190
192 isalpha(3C), isspace(3C), scanf(3C), strtod(3C), strtoul(3C),
193 attributes(5), standards(5)
194SunOS 5.11 6 May 2003 strtol(3C)