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Well, what I mean is that I dont see how in C the conditional is only evaluated once. I dont know enough about how C implements a case statement to say for sure But i dont see how a case statement could be implemented in such a way without adding a lot of code to the statement, which would potentially be far more expensive than converting it to a series of conditionals. For instance something like this

switch (val) { case 1 : handle_case1; break; case 2 : handle_case2; break; case 5 : handle_case5; case 10: handle_case10; default: handle_default; }

I would guess would get converted to something like

if (val == 1) { handle_case1; } elsif (val == 2) { handle_case2; } else { if (val == 5) { goto CASE5; } elsif (val == 10) { goto CASE10; } else { goto DEFAULT; } CASE5: handle_case5; CASE10: handle_case10; DEFAULT: handle_default; }

Or something like it. I just dont see how it could be handled otherwise. Perhaps the fact that it only operates on ints means that there is a neater optimisation. But if you extend switch to handle strings as it does in pascal then I think the situation becomes even more difficult.

Thanks to the CB for clarifying that switch only handles ints. That issue may make my ruminations on this invalid. I dont know. Id be interested to hear from someone that does. As I said, this issue confuses me. :-)


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In reply to Re: Re: Re: Re: Perl Idioms Explained: && and || "Short Circuit" operators by demerphq
in thread Perl Idioms Explained - && and || "Short Circuit" operators by davido

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    [erix]: record separator
    [Cosmic37]: Permissions are interesting earthlings. Did nature determine who gives permission and who asks permission. Who was the first to get permission? Are you not related to them as one big earthling family?
    [karlgoethebier]: Cojones! We need cojones!
    [karlgoethebier]: Ouch! Permissions! We need permissions!
    [BarApp]: I can not use modules. I gain temporary access and still can not use modules.
    [Cosmic37]: ta erix - this szabo geezer is pretty cool methinks and he writes about undef but I cannot see instructions for redefining the record separator after having undefined it

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