Showing entries with tag "Array".

Found 9 entries

Perl: Remove an item from array

If you want to remove an item from an array you can use a inverse grep filter like this:

my @x = qw(foo bar baz orange);
@x    = grep { !/orange/ } @x;


my @x = qw(foo bar baz orange);
@x    = grep { $_ ne 'orange' } @x;
Leave A Reply

Perl: Find unique items in an array

I need to extract all the unique elements from an array. There is no built-in way to do this, but there are several user functions you can use.

my @x = qw(one two one three one four);
my @y = array_unique(@x); # ("one", "two", "three", "four")
# Borrowed from:
sub array_unique {
    my %seen;
    return grep { !$seen{$_}++ } @_;

I stand corrected, List::Util includes a uniq() function to do exactly this, is a core module, and is included with all Perl installations.

Leave A Reply

Perl: Extract a column from a hashref

I have an array full of hash references and I need to extract a column and build an array from that.

my @x = ( {'ip' => ''}, {'ip' => ''}, {'ip' => ''} );
my @y = hash_column('ip', @x); # ["", "", ""]
sub hash_column {
    my $col = shift();
    my @arr = @_;

    my @ret;
    foreach my $x (@arr) {
        push(@ret, $x->{$col});

    return @ret;
Leave A Reply

Perl: Find the longest string in an array

I need a Perl way to find the maximum string length in an array so here is a function to do that:

my @words = qw(Apple Pear Watermelon Banana Cherry);
my $max   = max_length(@words); # 10
sub max_length {
    my $max = 0;

    foreach my $item (@_) {
        my $len = length($item);
        if ($len > $max) {
            $max = $len;

    return $max;
Leave A Reply

Perl: array_chunk() to split arrays into smaller chunks

I have an large array in Perl that I need in smaller chunks to make iteration easier. I borrowed a concept from PHP and implemented array_chunk() in Perl.

my @orig = qw(foo bar baz one two three red yellow green donk);
my @new  = array_chunk(3, @orig);
sub array_chunk {
    my ($num, @arr) = @_;
    my @ret;

    while (@arr) {
        push(@ret, [splice @arr, 0, $num]);

    return @ret;
Leave A Reply

Perl: find the index of an array item

I needed to find the index of an item in an array so I wrote a simple Perl function.

my @arr = qw(foo bar baz donk);
my $x   = array_index("bar", @arr)); # 1
sub array_index {
    my ($needle, @haystack) = @_;

    if (defined($needle)) {
        for (my $idx = 0; $idx < @haystack; $idx++) {
            if ($haystack[$idx] eq $needle) {
                return $idx;

    return undef;
Leave A Reply - 1 Reply

Perl: doing a regexp replace on an array

I have an array of items that I want to do a quick regexp replace on each element. Here is a very elegant solution:

@names = ("John", "Paul", "george", "Ringo");
s/^g/G/g for @names;
print join(", ",@names);
Leave A Reply

Remove an item from a PHP array

Given an array in PHP, I need to remove a specific element (if it exists in the array) from the array. The following is a pretty simple and elegant solution. I didn't use unset on purpose because you have to check for a integer result before you remove the item from the array.

$arr     = array('apple','banana','orange');
$new_arr = array_diff($arr, array('banana'));

Leave A Reply

Perlfunc: in_array()

If you need to determine if an array contains a specific element you can use this function:

sub in_array {
    my ($needle, @haystack) = @_;

    foreach my $l (@haystack) {
        if ($l eq $needle) { return 1; }

    return 0;

Note: If you want to check integers just change the eq to ==

Leave A Reply