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splice returns the array elements that were removed from the original array. All offsets in Perl are zero based.
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@a = 0..10;
$[ = 2;
warn $a[2];
warn splice(@a, 2, 1, 6);
warn @a;
__END__
0 at - line 3.
0 at - line 4.
612345678910 at - line 5.
| [reply]
[d/l] |
Just a small note about your suggestion.
I think changing $[ is very dangerous thing to do since the it is almost always 0. So if you need to change it for some reason make sure the change is local to the smallest scope needed.
Thanks!
I have spent too much time debugging my program on one occation when a module changed this globally ...
si_lence
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my @foo = qw/1 2 3 4 5 6/;
print "Index 1 is $foo[1]\n";
Do that, and it should be obvious :)
Update: duh, that was a really poor example, given that your question is about splice. Here is a better example:
my @foo = qw/1 2 3 4 5 6/;
my @bar = splice @foo, 1,2;
print "Indexes 1 & 2 are @bar\n";
| [reply]
[d/l]
[select] |
I think biohisham means the index used in the offset for the splice function.
But similarly,
perl -le 'my @arr = qw/1 2 3/; print "Removing ",splice(@arr,1,1), "\n
+"; print join(" - ", @arr), "\n"'
Does show you that it is indeed 0-based (by default). | [reply]
[d/l] |
Hi biohisham,
With the splice operator, you can add items to the middle of an array or remove them, letting the array grow or shrink as needed. The portion that is removed starts at the OFFSET element of the array and continues for LENGTH elements. If the LENGTH is not specified, it will cut to the end of the array.
@LIST = splice(@ARRAY, OFFSET, LENGTH, @REPLACE_WITH);
Eg:
Cuttinmg out some elements of one array into another
@myNames = ('Jacob', 'Michael', 'Joshua', 'Matthew', 'Ethan', 'Andrew');
@someNames = splice(@myNames, 1, 3);
Think of the @myNames array as a row of numbered boxes, going from left to right, numbered starting with a zero. The splice() function would cut a chunk out of the @myNames array starting with the element in the #1 position (in this case, Michael) and ending 3 elements later at Matthew. The value of @someNames then becomes ('Michael', 'Joshua', 'Matthew'), and @myNames is shortened to ('Jacob', 'Ethan', 'Andrew').
Replacing some elements of an array with other elements:
As an option, you can replace the portion removed with another array by passing it in the REPLACE_WITH argument.
@myNames = ('Jacob', 'Michael', 'Joshua', 'Matthew', 'Ethan', 'Andrew');
@moreName = ('Daniel', 'William', 'Joseph');
@someNames = splice(@myNames, 1, 3, @moreName);
In the above example, the splice() function would cut a chunk out of the @myNames array starting with the element in the #1 position (in this case, Michael and ending 3 elements later at Matthew. It then replaces those names with the contents of the @moreNames array. The value of @someNames then becomes ('Michael', 'Joshua', 'Matthew'), and @myNames is changed to ('Jacob', 'Daniel', 'William', 'Joseph', 'Ethan', 'Andrew').
Gyatso | [reply] |
AHA, that means this replacement is actually mutual, the second array, @someNames gives to @myNames 3 elements and takes from @myNames 3 elements or whatever the size is for that matter.
the offset is zero based.... and a combination of OFFSET, LENGTH, REPLACEMENT_ARRAY(or LIST) is so powerful
Thanks Gyatso
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oops...no, I meant the other way around, this replacement is not mutual,.. that is what I meant to say.. since we have three arrays involved in there
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