```{index} single: strtoul; POSIX function ``` ```{index} single: POSIX::strtoul; Perl function ``` # strtoul Parse an unsigned integer from the start of a string, in a given base. ## Synopsis ```perl use POSIX qw(strtoul); my ($n, $unparsed) = strtoul("255 end", 10); ``` ## Edge cases - Invalid base: returns `(undef, undef)` and sets `$!` to `EINVAL`. - Negative input: parsed and two's-complement-cast to unsigned, matching C `strtoul`. ## Differences from upstream Fully compatible with upstream POSIX. ## See also - `strtol` — signed variant.