While 0 and 1 evaluate to false and true when tested, there is (was?) no real boolean type.

And !!0 is a special dual var, which is "" in string, and 0 in numeric context

Not having Booleans in Perl makes converting data from and to JSON problematic.

I seem to remember that Booleans were introduced with one of the last Perl releases.

So using !!0 and !!1 is both backwards and forward compatible.

Think of them as replacements for the keywords true and false found in languages like JS

Cheers Rolf
(addicted to the Perl Programming Language :)
see Wikisyntax for the Monastery

In reply to Re: Why is Dumper returning "!!1" for true file test? by LanX
in thread Why is Dumper returning "!!1" for true file test? by nysus

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