strtoul - convert a string to an unsigned long integer.
unsigned long int strtoul(const char *nptr, char **endptr,
The strtoul() function converts 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
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' 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 char-
acter 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'
If endptr is not NULL, strtoul() stores the address of the
first invalid character in *endptr. If there were no digits
at all, strtoul() stores the original value of nptr in
*endptr. (Thus, if *nptr is not `\0' but **endptr is `\0'
on return, the entire string is valid.)
The strtoul() function returns either the result of the
conversion or, if there was a leading minus sign, the nega-
tion 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 variable
errno to ERANGE.
The given string was out of range; the value converted
has been clamped.
SVID 3, BSD 4.3, ISO 9899
atof(3), atoi(3), atol(3),
Ignores the current locale.