Coolest Perl trick I've learned recently:
sub is_numeric {
($_[0] & ~ $_[0]) eq "0";
}
I found this gem when I was reading this thread about DBI::PurePerl.
Re:Explain this then!
IlyaM on 2002-05-31T07:15:17
It is based on the fact that operator '~' gives different result if it given string argument instead of numeric.
DB<4> p ~ 100
4294967195
DB<5> p ~ '100'
XXX
where XXX some chars from second half of ASCII table.
With numeric argument '~' acts as usual bitwise negation operator. With string argument it acts like
join '', map chr((~ord) & 255), split//, $arg
