in reply to (tye)Re2: forcing numeric context
in thread forcing numeric context

Isn't !1 just an expression that returns 0? No, trying it shows blank. It seems to be a zero-length string. So why is it different from ''? Is it magic?

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(tye)Re3: forcing numeric context
by tye (Sage) on Dec 18, 2002 at 15:39 UTC

    !1 returns Perl's "false" value. You can get the same effect via: 

    sub false {
    my $f= "";
    {
        BEGIN {
            warnings->unimport()   if  $INC{"warnings.pm"};
        }
        local( $^W )= 0;
        my $temp= 0+$f;
    }
    return $f;
}

    [download]
    That is, the "false" value simply has a string value of "" and a numeric value of 0. Thus there is no warning when in numeric context since the 0 is simply fetched rather that it having to be computed from the empty string.

            - tye
[reply]
[d/l]
[reply]
      So, the numeric value is already cached in the value, so it doesn't generate a warning because it doesn't re-compute it. Right? Very interesting.
[reply]

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