David L. Nicol writes:
> Why not use an explicit perl5 counter?
>
> my $index;
> foreach $item (@array){ $index++;
> print $item, " is at index ", $index, "\n";
> }
Well, one reason is that your example doesn't work (it starts the
index at 1 instead of 0). You'd need to do
my $index = -1;
foreach $item (@array){ $index++;
print $item, " is at index ", $index, "\n";
}
to get it to work. But that would break if you had a `redo' in the
loop (it would increment $index when it shouldn't). You could fix
that by moving the increment to the end of the loop:
my $index = 0;
foreach $item (@array){
print $item, " is at index ", $index, "\n";
++$index;
}
But that would break if you had a `next' (it wouldn't increment $index
when it should). The correct way to do this is:
my $index = 0;
foreach $item (@array){
print $item, " is at index ", $index, "\n";
} continue {
++$index;
}
And you still couldn't be sure that $index really was what it claimed
to be except by carefully examining the loop body (easy for this
trivial loop, but not necessarily so). With the explicit counter,
foreach $item $index (@array) { ... }
$index could (and should) be a read-only variable (like $i is in
"foreach $i (1,2,3,4)"). This would make sure that it really was the
index it claimed to be.
--
Chris Madsen http://www.trx.com [EMAIL PROTECTED]
TRX Technology Services (214) 346-4611
