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Re^2: For vs. While

by Andrew_Levenson (Hermit)
on Dec 06, 2006 at 00:54 UTC ( #588010=note: print w/replies, xml ) Need Help??

in reply to Re: For vs. While
in thread For vs. While

Ahh, that makes perfect sense. Thanks!
V(qw/74 401 211 79/);sub V{while(@_){$v**=$V?$#_:$V; print(map{$V<$v?chr(shift):chr(reverse(pop))}$_),$V+=$#_%2!=1?1:0}}

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Re^3: For vs. While
by ikegami (Pope) on Dec 06, 2006 at 01:10 UTC

    That behaviour is specifically for for (@array). for (@array) is different than other forms of for (LIST). As soon as one iterates over anything but just an array, it's the size of the list on the stack that matters.

    The real difference is that for (@array) is optimized to avoid flattening @array onto the stack. Instead, for (@array) navigates @array in place. For all other expressions, a list is formed on the stack and for iterates over that.

    The following show the difference between iterating in place, and iterating over a list on the stack.

    sub f4 { for (@_) { print($_); shift; } print("\n"); } sub f5 { for ((), @_) { print($_); shift; } print("\n"); } f4(map/./g, Japh); # Jp f5(map/./g, Japh); # Japh

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