Re^4: iterating through array and saving matches to new array

[Marshall]

Yes, actually it would be. Although I would still prefer the block form of grep.
I show how to use map{}

It actually took me quite a while to learn how to return "nothing" instead of "undef" from a map.

[AnomalousMonk]

... how to return "nothing" instead of "undef" from a map.

That is a bit tricky :)

[Marshall]

I use grep to get a subset of an array.
I use map to transform an array into another array.
Special syntax for map can be used to do both, in certain situations.

UPDATE: I have now forgotten the exact code that I used to "return nothing", but something like this (untested) should work:

map{some condition ? $val : ()}@array;

This () is not "undefined", it is absolutely nothing. Of course it it possible to combine map and grep to filter out undefined values. I remember doing this for some reason, but it's been a few years. If someone wants to do this, just knowing that it is possible will get you started. perl doc map for more info.

[AnomalousMonk]

c:\@Work\Perl\monks>perl -wMstrict -MData::Dump -le
"my @ra = (1 .. 5);
 ;;
 my @rb = map { $_ == 3 ? () : $_ } @ra;
 dd \@rb;
"
[1, 2, 4, 5]