STRTOUL(3P)                                         POSIX Programmer's Manual                                        STRTOUL(3P)



PROLOG
       This  manual  page is part of the POSIX Programmer's Manual.  The Linux implementation of this interface may differ (con-
       sult the corresponding Linux manual page for details of Linux behavior), or the  interface  may  not  be  implemented  on
       Linux.

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  wish-
       ing 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 per-
       formed, 0 shall be returned  and errno may be set to [EINVAL].  If the correct value  is  outside  the  range  of  repre-
       sentable 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,  Copy-
       right (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.open-
       group.org/unix/online.html .



IEEE/The Open Group                                           2003                                                   STRTOUL(3P)