STRTOUL(3)                                                   Linux Programmer's Manual                                                  STRTOUL(3)

NAME

       strtoul, strtoull, strtouq - convert a string to an unsigned long integer

SYNOPSIS

       #include <stdlib.h>

       unsigned long int strtoul(const char *nptr, char **endptr, int base);

       unsigned long long int strtoull(const char *nptr, char **endptr,
                                       int base);

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       strtoull():
           _ISOC99_SOURCE ||
               || /* Glibc versions <= 2.19: */ _SVID_SOURCE || _BSD_SOURCE

DESCRIPTION

       The  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).

       The remainder 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' 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 '' but **endptr is '' on return, the
       entire string is valid.

       The strtoull() function works just like the strtoul() function but returns an unsigned long long int value.

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).

ERRORS

       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).

ATTRIBUTES

       For an explanation of the terms used in this section, see attributes(7).

       +---------------------------------+---------------+----------------+
       |Interface                        | Attribute     | Value          |
       +---------------------------------+---------------+----------------+
       |strtoul(), strtoull(), strtouq() | Thread safety | MT-Safe locale |
       +---------------------------------+---------------+----------------+
CONFORMING TO

       strtoul(): POSIX.1-2001, POSIX.1-2008, C89, C99 SVr4.

       strtoull(): POSIX.1-2001, POSIX.1-2008, C99.

NOTES

       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 int value.

EXAMPLE

       See the example on the strtol(3) manual page; the use of the functions described in this manual page is similar.

SEE ALSO

       a64l(3), atof(3), atoi(3), atol(3), strtod(3), strtol(3)

COLOPHON

       This  page is part of release 4.15 of the Linux man-pages project.  A description of the project, information about reporting bugs, and the
       latest version of this page, can be found at https://www.kernel.org/doc/man-pages/.

GNU                                                                 2017-09-15                                                          STRTOUL(3)