map takes a code block or an expression and evaluates it for each element in
a list
for example...
my @arr = (1,2,3,4,5);
my @arr2 = map {$_ + 3} @arr; # notice no comma
print "@arr2\n";
4 5 6 7 8
So, each element of @arr had 3 added to it.
Another example, using an expression would be
my @arr2 = map(chr, (65, 66, 67));
print "@arr2\n";
A B C
This took the expression (chr) and mapped it over the list (65, 66, 67)
which caused each
number to be changed to its character equivalent.
If you have a general expression
my @arr2 = map BLOCK LIST
you can think of it as being
foreach (LIST) {
BLOCK;
push( $_, @arr2 );
}
So, the purpose of map is to change every element of an array in the same
way and create a new array with those changed elements. You may also wish
to look at map's cousin grep, which works in a similar fashion, but is used
to find elements in an array that match a certain criteria.
perldoc -f map
perldoc -f grep
Tanton
----- Original Message -----
From: "Mystik Gotan" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Sunday, November 24, 2002 8:27 AM
Subject: I need some explainment on the MAP() Function
> My last question... It's getting a bit too much.. I'm sorry for asking so
> much.. But I find it quite hard to understand the map() function. Can
> anybody explain this?
>
> Again, apologise for asking so much. But I'm just a 14 year old Dutch boy
so
> sometimes it's a bit hard to follow the English references telling all
about
> OO Programming and stuff. I'm getting on quite good with Perl. I think
> that's nice, cause I haven't seen any 14 year old Perl programmers. I'm
not
> saying I am, I did however wrote some scripts which come in handy quite
> nicely.
>
> Any good explainment on the MAP function is really appreciated, since I
only
> really get 50% of the picture (it evaluates two variables with eatchother,
I
> suppose?).
>
>
>
> Sincerly,
> Bob Erinkveld
> (Webmaster Insane Hosts)
> www.insane-hosts.net
>
>
>
>
> _________________________________________________________________
> Direct chatten met je vrienden met MSN Messenger http://messenger.msn.nl
>
>
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>
>
>
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