in reply to Re^3: "last expression" quiz
in thread "last expression" quiz

Actually, a for loop does return something. Assuming it runs at least once, it will return an empty string, alias scalar false.

There seems to be no particular reason for that behaviour.

Makeshifts last the longest.

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Re^5: "last expression" quiz
by sauoq (Abbot) on Oct 19, 2005 at 22:36 UTC

    Actually, bart is saying it returns !1 which is really scalar false. It is subtly different than "" as can be seen here: 

    $ perl -wle 'print "yes" if !1 == 0 '
yes
$ perl -wle 'print "yes" if "" == 0 '
Argument "" isn't numeric in numeric eq (==) at -e line 1.
yes

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    -sauoq
"My two cents aren't worth a dime.";
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      The difference is more visible this way: 
      use Devel::Peek;
Dump("");
Dump(!1);

      [download]
      The output of which is 
      SV = PV(0x816d944) at 0x8163c48
  REFCNT = 1
  FLAGS = (PADBUSY,PADTMP,POK,READONLY,pPOK)
  PV = 0x8167830 ""\0
  CUR = 0
  LEN = 1
SV = PVNV(0x814d6a0) at 0x814c600
  REFCNT = 2147483647
  FLAGS = (PADBUSY,PADTMP,NOK,POK,READONLY,pNOK,pPOK)
  IV = 0
  NV = 0
  PV = 0x814d678 ""\0
  CUR = 0
  LEN = 1
      Jeff japhy Pinyan, P.L., P.M., P.O.D, X.S.: Perl, regex, and perl hacker
      How can we ever be the sold short or the cheated, we who for every service have long ago been overpaid? ~~ Meister Eckhart
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      Ah, interesting; I guess Perl DWIMs this so well I had never paid enough attention to notice the subtlety. Reminds me of the games some people played elsewhere on the Monastery quite a while ago with scalars that had specific, different values when evaluated as numbers or as strings (without overloading, if memory serves). (Alas, I cannot remember any useful keywords to Super Search it.)

      Makeshifts last the longest.

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