NAME

strtoul - convert a string to an unsigned long integer

SYNOPSIS

#include <stdlib.h>

#include <limits.h>

unsigned long strtoul(const char *nptr, char **endptr, int base);

DESCRIPTION

Strtoul converts the string in nptr to an unsigned long
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; see ctype(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 value

in the obvious manner, stopping at the end of the string or
at the

first character that does not produce 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 non nil, strtoul
stores the address of the first

invalid character in *endptr. If there were no digits at
all,

however, strtoul stores the original value of nptr in
*endptr.

(Thus, if *nptr is not ’ ’ but **endptr is
’ ’ on return, the

entire string was valid.)

RETURN VALUE

Strtoul 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 errno
to

ERANGE.

ERRORS

[ERANGE]

The given string was out of range; the value converted has

been clamped.

SEE ALSO

strtol(3)

STANDARDS

Strtoul conforms to ANSI X3.159-1989 ("ANSI
C").

BUGS

Ignores the current locale.