RE: for loops

When using multiple initializations in a for loop, I found that scoping didn't work as I expected it would. For example, in this fake snippet

use strict;
### this code contains an error
for (my $i=1,
     my $j = $i + 100;
     $i<50;
     $i++, $j++) {
    print "i=$i j=$j hello!\n";
}
[download]

the line

     my $j = $i + 100;
[download]

generates an error because $i doesn't exist yet. Not a big deal, and trivial to work-around, but can someone explain why scoping works this way here? nop

Comment on RE: for loops Select or Download Code

Replies are listed 'Best First'.
RE: RE: for loops by mirey (Initiate) on Nov 02, 2000 at 04:51 UTC
I do not think you are looking at a scope issue. You are including code in the defenition of your for loop. Try this: for($i; $i < 50; $i++) { $j = $i + 100; $j++; print "i=$i j=$j hello!\n"; } Another question would be why do you have $j = $i + 100; and $j++; instead combine them the following way $j = $i + 101;	[reply]
Re^2: for loops by hossman (Prior) on Oct 11, 2004 at 01:09 UTC
can someone explain why scoping works this way here? That question implies that the scoping works differently elsewhere -- it doesn't. you get that error regardless of the for loop... `laptop:~> perl -Mstrict -e 'my $i=1, my $j=$i+1; print $i + $j;' Global symbol "$i" requires explicit package name at -e line 1. Execution of -e aborted due to compilation errors.` [download] ...the behavior of the comma oporator is not changed by being used in a for loop.	[reply] [d/l]
Re^2: for loops by apotheon (Deacon) on Oct 11, 2004 at 00:58 UTC
Because the value of $j has no bearing on the test expression, it doesn't belong in the initial and change expressions of the for statement. As such, they should be included in the set of code executed by the loop. - apotheon CopyWrite Chad Perrin	[reply]