Perl/Basics/Variables and Data Types/Arrays
Arrays (or lists) have elements. Typically an array in perl can contain anything - each element can be something different. An array element may be a hash, hash reference, scalar, or another array.
Arrays are prefixed by the @ character:
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<syntaxhighlight lang="perl">my @messages = ("Hello world!\n","I like perl!\n"); print $messages[0]; print $messages[1]; print "Size of messages array: ". $#messages . "\n"; </syntaxhighlight> |
You can access and modify array elements directly:
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<syntaxhighlight lang="perl"> $messages[0] = "Hello world!\n"; </syntaxhighlight> |
Helper Functions
join()
Join will compile an array into a scalar. Using the array example above, @messages, the following code will generate the string "Hello world!\n, I like perl!\n" as a scalar:
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<syntaxhighlight lang="perl">my @messages = ("Hello world!\n","I like perl!\n"); my $joined_message = join(", ",@messages); print $joined_message;</syntaxhighlight> |
split()
Split takes a scalar and converts it to an array using a delimiter. Using our string from earlier:
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<syntaxhighlight lang="perl">my $joined_message = "Hello world!\n, I like perl!\n"; my @messages = split('/, /',$joined_message); print $messages[0]; print $messages[1]; print "Size of messages array: ". $#messages . "\n";</syntaxhighlight> |
push()
The push() function is used to append an element or elements to the end of an array, similar to the push instruction in assembly and treats the array like a stack.
my @array; push(@array,'element one'); push(@array,('element two','element three')); |
$array[$#array] = "new element";
pop()
The pop() function is similar to the pop instruction in assembly and treats the array like a stack.
my @array; $array[$#array] = 1; $popped = pop(@array); |
The same affect can be acheived with:
$popped = $array[$#array--]; |
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Executing pop() on an array will delete the highest order array element. |
unshift()
The unshift() function is like the inverse of the push() function and treats the array like a stack. In stead of pushing to the top of the stack, this function operates against the bottom of the stack.
my @array; $array[0] = 1; unshift(@array,0); # $array[0] now contains "0" and $array[1] now contains [1]. |
shift()
The shift() function is like the inverse of the pop() function and treats the array like a stack. In stead of popping from the top of the stack, this function operates against the bottom of the stack.
my @array = (0,1); my $first_element = shift(@array); # $array[0] now contains one, and @array only contains one element |
