Ways to Flatten A Perl Array in Scalar Context

Question

I recently started learning perl and have a question that I'm not finding a clear answer to on the Internet. say I have something like this,

@arr = (1, 2, 3); $scal = "@arr" # $scal is now 123. 

Is the use of quotes the only way to flatten the array so that each element is stored in the scalar value? It seems improbable but I haven't found any other ways of doing this. Thanks in advance.

Answer 1

The join function is commonly used to "flatten" lists. Lets you specify what you want between each element in the resulting string.

$scal = join(",", @arr); # $scal is no "1,2,3" 

Answer 2

In your example, you're interpolating an array in a double-quoted string. What happens in those circumstances is is controlled by Perl's $" variable. From perldoc perlvar:

$LIST_SEPARATOR

$"

When an array or an array slice is interpolated into a double-quoted string or a similar context such as /.../ , its elements are separated by this value. Default is a space. For example, this:

print "The array is: @array\n";

is equivalent to this:

print "The array is: " . join($", @array) . "\n";

Mnemonic: works in double-quoted context.

The default value for $" is a space. You can obviously change the value of $".

{   local $" = ':',   my @arr = (1, 2, 3);   my $scalar = "@arr"; # $scalar contains '1:2:3' } 

As with any of Perl's special variables, it's always best to localise any changes within a code block.