I have once again forgotten how to get $_ to represent an array when it is in a loop of a two dimensional array.
foreach(@TWO_DIM_ARRAY){
my @ARRAY = $_;
}
That's the intention, but that doesn't work. What's the correct way to do this?
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Can you show the data you are starting with and what you want to end up with, even if in pseudocode?brian d foy– brian d foy2010-10-14 21:44:57 +00:00Commented Oct 14, 2010 at 21:44
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3 Answers
The line my @ARRAY = @$_; (instead of = $_;) is what you're looking for, but unless you explicitly want to make a copy of the referenced array, I would use @$_ directly.
Well, actually I wouldn't use $_ at all, especially since you're likely to want to iterate through @$_, and then you use implicit $_ in the inner loop too, and then you could have a mess figuring out which $_ is which, or if that's even legal. Which may have been why you were copying into @ARRAY in the first place.
Anyway, here's what I would do:
for my $array_ref (@TWO_DIM_ARRAY) {
# You can iterate through the array:
for my $element (@$array_ref) {
# do whatever to $element
}
# Or you can access the array directly using arrow notation:
$array_ref->[0] = 1;
}
3 Comments
sorpigal
+1 for the for my $var syntax. Seems like a lot of people don't bother with this, though it improves readability quite a lot.
Michael Goldshteyn
Still, why doesn't this work: foreach(@TWO_DIM_ARRAY){ print join ',',@{$_}; } After all, $_ is an array reference, and @{$_} should be an array.
Jander
@Michael Goldshteyn: That will work too.
@{$_} is the same as @$_. For example, I just tried this: my @A=([1,2,3],[4,5,6],[7,8,9]); foreach(@A) { print join(",", @{$_}), "\n"; }for (@TWO_DIM_ARRAY) {
my @arr = @$_;
}
Comments
The $_ will be array references (not arrays), so you need to dereference it as:
my @ARRAY = @$_;