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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


In reply to Re^3: grep flip flop (range operator) by davido
in thread grep flip flop (range operator) by Anonymous Monk

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