strtoul

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);

DESCRIPTION
       The strtoul() function converts the initial part of the string in nptr
       to  an  unsigned long integer value according to the given base, which
       must be between 2 and 36 inclusive, or be the special value 0.

       The string must 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’	 pre-
       fix, 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 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,	 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 integer 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, unless the original (non-negated) value would overflow; in
       the latter case, strtoul() returns ULONG_MAX and sets the global vari-
       able errno to ERANGE.  Precisely the same holds for  strtoull()	(with
       ULLONG_MAX instead of ULONG_MAX).

ERRORS
       ERANGE The resulting value was out of range.

       EINVAL (not in C99) The given base contains an unsupported value.

       The  implementation may also set errno to EINVAL in case no conversion
       was performed (no digits seen, and 0 returned).

NOTES
       In locales other than the  "C"  locale,	also  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().

CONFORMING TO
       strtoul() conforms to SVID 3, BSD 4.3, ISO 9899 (C99) and  POSIX,  and
       strtoull() to ISO 9899 (C99) and POSIX 1003.1-2001.

SEE ALSO
       atof(3), atoi(3), atol(3), strtod(3), strtol(3)



GNU				  2002-05-30			   STRTOUL(3)