The perlsyn doc says that "foreach" is a synonym for "for", so the two are
indeed interchangable. But you should also note that there are 2 different
"modes" in which the for/foreach statement works.
If you use it in the C-style "for($x=1; $x<10; $x++) {}" way, then $x is not
localized to the loop (unless you declare it with "my" as part of the for()
loop). Use this mode if you want to modify $x within the loop and have the
value of $x persist even after the loop exits.
$x = "hello";
foreach ($x=1; $x < 5; $x++) {
print "x = $x\n";
}
print "done. x = $x\n";
Results in:
x = 1
x = 2
x = 3
x = 4
done. x = 5
The other mode is the more foreach-ish one... "foreach $x (1 .. 10) {}".
The difference here is that the value of $x is localized (ie. hidden away
and then restored when the loop exits) implicitly. For example:
my $x = "hello";
for $x (1 .. 5) {
print "x = $x \n";
}
print "done. x = $x\n";
Results in:
x = 1
x = 2
x = 3
x = 4
x = 5
done. x = hello
I'm not sure why they didn't just keep them separate because, to me, it
makes things more confusing since most people are used to seeing "for" used
in the C-style way and "foreach" used in the C-shell-style way, not
vice-versa (as I just did). The localization feature is nice but it
certainly makes perl seem hard for beginners.
-- Brad
> On Fri, 2002-03-01 at 14:52, James Taylor wrote:
> > I'm really curious what the point of foreach is considering for does the
same
> > exact thing? For example:
> >
> > @myarray = (1 .. 10);
> >
> > for (@myarray) {
> > print "$_\n";
> > }
> >
> >
> > Or, you could swap the for for a foreach and the same thing would get
> > accomplished... The only difference I can think of is a slightly
different
> > handling of hashes. Is this the only benefit of foreach? What am I
missing
> > here
>
> It is my understanding that for and foreach were once different, but now
> the same. Which would mean that foreach is still here for backward
> compatibility and style reasons.
>
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