strtoull, strtouq − convert a string to an unsigned
long int strtoul(const char *nptr, char
**endptr, int base);
long long int strtoull(const char *nptr, char
Macro Requirements for glibc (see
_XOPEN_SOURCE >= 600
|| _BSD_SOURCE || _SVID_SOURCE || _ISOC99_SOURCE ||
_POSIX_C_SOURCE >= 200112L;
or cc -std=c99
strtoul() function converts the initial part of the
string in nptr to an unsigned long int 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).
of the string is converted to an unsigned long int
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'
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
strtoull() function works just like the
strtoul() function but returns an unsigned long
long int value.
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).
(not in C99) The given
base contains an unsupported value.
The resulting value was out of range.
implementation may also set errno to EINVAL in
case no conversion was performed (no digits seen, and 0
explanation of the terms used in this section, see
POSIX.1-2001, POSIX.1-2008, C89, C99 SVr4.
POSIX.1-2001, POSIX.1-2008, C99.
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.
other than the "C" locale, other strings may be
accepted. (For example, the thousands separator of the
current locale may be supported.)
strtouq(const char *nptr, char
**endptr, int base);
analogous definition. Depending on the wordsize of the
current architecture, this may be equivalent to
strtoull() or to strtoul().
are considered valid input and are silently converted to the
equivalent unsigned long int value.
See the example
on the strtol(3) manual page; the use of the
functions described in this manual page is similar.
atoi(3), atol(3), strtod(3),
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