NAME

       strtoul, strtoull - convert a string to an unsigned long

SYNOPSIS

       #include <stdlib.h>

       unsigned long strtoul(const char *restrict str,
              char **restrict endptr, int base);
       unsigned long long strtoull(const char *restrict str,
              char **restrict endptr, int base);

DESCRIPTION

       These  functions  shall  convert  the initial portion of the string pointed to by str to a
       type unsigned long and  unsigned  long  long  representation,  respectively.  First,  they
       decompose the input string into three parts:

        1. An  initial,  possibly  empty,  sequence  of  white-space  characters (as specified by
           isspace())

        2. A subject sequence interpreted as an integer represented in some radix  determined  by
           the value of base

        3. A  final string of one or more unrecognized characters, including the terminating null
           byte of the input string

       Then they shall attempt to convert the subject sequence to an unsigned integer, and return
       the result.

       If  the value of base is 0, the expected form of the subject sequence is that of a decimal
       constant, octal constant, or hexadecimal constant, any of which may be preceded by  a  '+'
       or  '-'  sign. A decimal constant begins with a non-zero digit, and consists of a sequence
       of decimal digits. An octal constant consists of the prefix '0' optionally followed  by  a
       sequence  of the digits '0' to '7' only.  A hexadecimal constant consists of the prefix 0x
       or 0X followed by a sequence of the decimal digits and letters 'a' (or 'A' )  to  'f'  (or
       'F' ) with values 10 to 15 respectively.

       If  the  value of base is between 2 and 36, the expected form of the subject sequence is a
       sequence of letters and digits representing an integer with the radix specified  by  base,
       optionally  preceded by a '+' or '-' sign. The letters from 'a' (or 'A' ) to 'z' (or 'Z' )
       inclusive are ascribed the values 10 to 35; only letters whose ascribed  values  are  less
       than  that  of base are permitted. If the value of base is 16, the characters 0x or 0X may
       optionally precede the sequence of letters and digits, following the sign if present.

       The subject sequence is defined as the longest initial subsequence of  the  input  string,
       starting  with  the  first  non-white-space  character  that  is of the expected form. The
       subject sequence shall contain no characters if the input  string  is  empty  or  consists
       entirely  of  white-space  characters,  or if the first non-white-space character is other
       than a sign or a permissible letter or digit.

       If the subject sequence has the expected form and the value of base is 0, the sequence  of
       characters  starting  with the first digit shall be interpreted as an integer constant. If
       the subject sequence has the expected form and the value of base is between 2 and  36,  it
       shall  be  used  as  the  base for conversion, ascribing to each letter its value as given
       above. If the subject sequence begins with a minus sign,  the  value  resulting  from  the
       conversion  shall  be negated. A pointer to the final string shall be stored in the object
       pointed to by endptr, provided that endptr is not a null pointer.

       In other than the C    or POSIX  locales, other implementation-defined  subject  sequences
       may be accepted.

       If  the  subject sequence is empty or does not have the expected form, no conversion shall
       be performed; the value of str shall be  stored  in  the  object  pointed  to  by  endptr,
       provided that endptr is not a null pointer.

       The strtoul() function shall not change the setting of errno if successful.

       Since 0, {ULONG_MAX}, and {ULLONG_MAX} are returned on error and are also valid returns on
       success, an application wishing to check for error situations should set errno to 0,  then
       call strtoul() or strtoull(), then check errno.

RETURN VALUE

       Upon  successful  completion, these functions shall return the converted value, if any. If
       no conversion could be performed, 0 shall be returned    and errno may be set to [EINVAL].
       If  the  correct  value  is  outside  the  range  of  representable values, {ULONG_MAX} or
       {ULLONG_MAX} shall be returned and errno set to [ERANGE].

ERRORS

       These functions shall fail if:

       EINVAL The value of base is not supported.

       ERANGE The value to be returned is not representable.

       These functions may fail if:

       EINVAL No conversion could be performed.

       The following sections are informative.

EXAMPLES

       None.

APPLICATION USAGE

       None.

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       isalpha()  ,  scanf()  ,  strtod()  ,  strtol()  ,  the   Base   Definitions   volume   of
       IEEE Std 1003.1-2001, <stdlib.h>

COPYRIGHT

       Portions  of  this  text  are  reprinted  and  reproduced in electronic form from IEEE Std
       1003.1, 2003 Edition, Standard for Information Technology  --  Portable  Operating  System
       Interface  (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 by
       the Institute of Electrical and Electronics Engineers, Inc and  The  Open  Group.  In  the
       event  of  any  discrepancy  between this version and the original IEEE and The Open Group
       Standard, the original IEEE and The Open Group  Standard  is  the  referee  document.  The
       original Standard can be obtained online at http://www.opengroup.org/unix/online.html .