преобразовать строку в длинное целое число без знака (convert a string to an unsigned long integer)
Имя (Name)
strtoul, strtoull, strtouq - convert a string to an unsigned long
integer
Синопсис (Synopsis)
#include <stdlib.h>
unsigned long strtoul(const char *restrict nptr,
char **restrict endptr, int base);
unsigned long long strtoull(const char *restrict nptr,
char **restrict endptr, int base);
Feature Test Macro Requirements for glibc (see
feature_test_macros(7)):
strtoull():
_ISOC99_SOURCE
|| /* Glibc <= 2.19: */ _SVID_SOURCE || _BSD_SOURCE
Описание (Description)
The strtoul() function converts the initial part of the string in
nptr to an unsigned long value according to the given base, which
must be between 2 and 36 inclusive, or be the special value 0.
The string may begin with an arbitrary amount of white space (as
determined by isspace(3)) followed by a single optional '+' or
'-' sign. If base is zero or 16, the string may then include a
"0x" prefix, and the number will be read in base 16; otherwise, a
zero base is taken as 10 (decimal) unless the next character is
'0', in which case it is taken as 8 (octal).
The remainder of the string is converted to an unsigned long
value in the obvious manner, stopping at the first character
which is not a valid digit in the given base. (In bases above
10, the letter 'A' in either uppercase or lowercase represents
10, 'B' represents 11, and so forth, with 'Z' representing 35.)
If endptr is not NULL, strtoul() stores the address of the first
invalid character in *endptr. If there were no digits at all,
strtoul() stores the original value of nptr in *endptr (and
returns 0). In particular, if *nptr is not '\0' but **endptr is
'\0' on return, the entire string is valid.
The strtoull() function works just like the strtoul() function
but returns an unsigned long long value.
Возвращаемое значение (Return value)
The strtoul() function returns either the result of the
conversion or, if there was a leading minus sign, the negation of
the result of the conversion represented as an unsigned value,
unless the original (nonnegated) value would overflow; in the
latter case, strtoul() returns ULONG_MAX and sets errno to
ERANGE. Precisely the same holds for strtoull() (with ULLONG_MAX
instead of ULONG_MAX).
Ошибки (Error)
EINVAL (not in C99) The given base contains an unsupported value.
ERANGE The resulting value was out of range.
The implementation may also set errno to EINVAL in case no
conversion was performed (no digits seen, and 0 returned).
Атрибуты (Attributes)
For an explanation of the terms used in this section, see
attributes(7).
┌───────────────────────────────┬───────────────┬────────────────┐
│Interface │ Attribute │ Value │
├───────────────────────────────┼───────────────┼────────────────┤
│strtoul(), strtoull(), │ Thread safety │ MT-Safe locale │
│strtouq() │ │ │
└───────────────────────────────┴───────────────┴────────────────┘
Стандарты (Conforming to)
strtoul(): POSIX.1-2001, POSIX.1-2008, C89, C99 SVr4.
strtoull(): POSIX.1-2001, POSIX.1-2008, C99.
Примечание (Note)
Since strtoul() can legitimately return 0 or ULONG_MAX
(ULLONG_MAX for strtoull()) on both success and failure, the
calling program should set errno to 0 before the call, and then
determine if an error occurred by checking whether errno has a
nonzero value after the call.
In locales other than the "C" locale, other strings may be
accepted. (For example, the thousands separator of the current
locale may be supported.)
BSD also has
u_quad_t strtouq(const char *nptr, char **endptr, int base);
with completely analogous definition. Depending on the wordsize
of the current architecture, this may be equivalent to strtoull()
or to strtoul().
Negative values are considered valid input and are silently
converted to the equivalent unsigned long value.
Примеры (Examples)
See the example on the strtol(3) manual page; the use of the
functions described in this manual page is similar.
Смотри также (See also)
a64l(3), atof(3), atoi(3), atol(3), strtod(3), strtol(3),
strtoumax(3)
