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.

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
[download]

-sauoq
"My two cents aren't worth a dime.";

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

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.

Oh, and another thing: you can use either 0 or 1 as a constant in void context without getting a warning, but you can also use any string that starts with "ig", "ds", or "di", as Dominus famously demonstrated.

Makeshifts last the longest.

as well as as the last statement in a required file/module.

Well, you can use whatever you want as the last statement of a required module without getting the "Useless use of a constant in void context" warning.

-sauoq
"My two cents aren't worth a dime.";

True, if you actually require the file. That probably is because then, the last statement isn't called in void context.

But you do get the warning if you try to test such a module for syntax errors using perl -wc FILE. Unless you actually use 1.