STRTOUL(3)



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

NAME
       strtoul, strtoull, strtouq - convert a string to an unsigned long inte-
       ger

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 || _POSIX_C_SOURCE >= 200112L;
           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 deter-
       mined 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, str-
       toul() 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 (non-
       negated) value would overflow; in the latter  case,  strtoul()  returns
       ULONG_MAX  and sets errno to ERANGE.  Precisely the same holds for str-
       toull() (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
   Multithreading (see pthreads(7))
       The strtoul(), strtoull(), and strtouq() functions are thread-safe with
       exceptions.  These functions can be safely used in multithreaded appli-
       cations,  as  long  as  setlocale(3) is not called to change the locale
       during their execution.

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 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 sup-
       ported.)

       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 str-
       toul().

       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 3.71 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
       http://www.kernel.org/doc/man-pages/.

GNU                               2014-03-18                        STRTOUL(3)

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