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Re^3: grep flip flop (range operator)

by davido (Archbishop)
on Sep 13, 2012 at 07:23 UTC ( #993389=note: print w/ replies, xml ) Need Help??


in reply to Re^2: grep flip flop (range operator)
in thread grep flip flop (range operator)

perl -E 'say "Yes!" if $. == 0;'

$. uninitialized if there's no file open for reading (undef). undef is false. In a numeric comparison, undef is promoted to zero (or conceptually better, zero is demoted to false, and undef is promoted to false). Consequently, 0 .. is true, and the flip flop flips.

If warnings were enabled you'd get one. :)


Dave

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Re^4: grep flip flop (range operator)
by frozenwithjoy (Priest) on Sep 13, 2012 at 07:26 UTC
    Ah, yes.... and the reason it doesn't stop at Q is because it gets flipped right back on after Q. Apparently, my brain only works once per night. Thanks!

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