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(): XOPEN_SOURCE >= 600 || _BSD_SOURCE || _SVID_SOURCE || _ISOC99_SOURCE; or cc -std=c99

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 char-
       acter which is not a valid digit in the given base.  (In bases above 10, the letter 'A' in either  upper  or  lower  case
       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 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).

CONFORMING TO
       strtoul() conforms to SVr4, C89, C99 and POSIX-2001, and strtoull() to C99 and POSIX.1-2001.

NOTES
       Since strtoul() can legitimately return 0 or LONG_MAX (LLONG_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  cur-
       rent 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
       atof(3), atoi(3), atol(3), strtod(3), strtol(3)

COLOPHON
       This page is part of release 3.25 of the Linux man-pages project.  A description of the project,  and  information  about
       reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.



GNU                                                        2007-07-26                                                 STRTOUL(3)