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Pointers and references: Difference between revisions
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'''Interpeter:''' [[Perl]] v5.x
References are essentially how perl handles pointers. Any scalar value, element in an array, key of a hash, or value of a hash may contain a reference to any other variable structurer.
# start with some var definitions
my $scalar = 'a string';
my @array = ('an', 'array');
my %hash = ( firstkey => 'a', secondkey => 'hash' );
# make pointers
my $scalarref = \$scalar;
my $arrayref = \@array;
my $hashref = \%hash;
Using a reference
# printing the value
print ${$scalar};
print $arrayref->[1]; # this would print "array"
print $hashref->{'secondkey'}; # this would print "hash"
# changing the value
${$scalar} = 'a new string'; # would change $scalar as well
$arrayref->[0] = 'an altered'; # would change the first value of @array as well
$hashref->{'firstkey'} = 'a good'; # would change the value of the firstkey name value pair in %hash
You may also create pointers or references without pointing to a previous variable.
my $scalarref;
${$scalarref} = 'a scalar';
my $arrayref = ['an', 'array'];
my $hashref = { firstkey => 'a', secondkey => 'hash' }
==[[Tcl]]==
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