STRTOUL(3) Library Functions Manual STRTOUL(3)
strtoul - convert a string to an unsigned long
strtoul(nptr, endptr, base)
The strtoul() function converts the string in nptr to an unsigned long value. The conversion is done 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(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 repre-
sents 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
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
variable errno to ERANGE .
[ERANGE] The given string was out of range; the value converted has been clamped.
The strtoul() function conforms to ANSI C X3.159-1989 (``ANSI C'').
Ignores the current locale.
4.4 Berkeley Distribution January 12, 1996 STRTOUL(3)