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Remember, that perl will evaluate a variable when it is called, and as such a viariable which is called at one time in the program can be changed and outputted diferently later.
The first assignment below explodes the @music variable so that it is equivalent to the second assignment.
@moremusic = ("organ", @music, "harp");
@moremusic = ("organ", "whistle", "flute", "harp");
This should suggest a way of adding elements to an array. A neater way of adding elements is to use the statement
push(@food, "eggs");
which pushes eggs onto the end of the array To push two or more items onto the array use one of the following forms:
push(@food, "eggs", "lard");
push(@food, ("eggs", "lard"));
push(@food, @morefood);
The push function returns the length of the new list.
To remove the last item from a list and return it use the pop function. From our original list the pop function returns eels and @food now has two elements:
$grub = pop(@food); # Now $grub = "eels"
It is also possible to assign an array to a scalar variable. As usual context is important. The line
$f = @food;
assigns the length of @food, but
$f = "@food";
turns the list into a string with a space between each element. This space can be replaced by any other string by changing the value of the special $" variable. This variable is just one of Perl's many special variables, most of which have odd names.
Arrays can also be used to make multiple assignments to scalar variables:
($a, $b) = ($c, $d); # Same as $a=$c; $b=$d;
($a, $b) = @food; # $a and $b are the first two
# items of
($a, @somefood) = @food; # $a is the first item of @food
# @somefood is a list of the
# others.
(@somefood, $a) = @food; # @somefood is @food and
# $a is undefined.
The last assignment occurs because arrays are greedy, and @somefood will swallow up as much of @food as it can. Therefore that form is best avoided.
Finally, you may want to find the index of the last element of a list. To do this for the @food array use the expression
$#food
Displaying Arrays
Remember, the context in which you call a variable is important, co the following will give diferent results:
print @food; # By itself
print "@food"; # Embedded in double quotes
print ""; # In a scalar context
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