Perl associative array (hash) and array

refer to :?http://www.thegeekstuff.com/2011/09/perl-complex-data-structures/ and?http://www.perlmonks.org/?node_id=1978

Perl developers should understand how to use complex data structures effectively. In this article,I picked the top 5 useful posts about complex data structures from perlmonks,and gave simple examples on how to use them. 1. Perl Array of Arrays The following example defines a sample perl array of arrays. @tgs = ( ['article series','sed & awk','troubleshooting','vim','bash'],['ebooks','linux 101','vim 101','nagios core','bash 101' ] ); To access a single element,for example,to Access 2nd element from the 1st array,do the following: $tgs[0][1]; Access all the elements one by one as shown below. print @$_,"n" foreach ( @tgs ); Read more: How do I make an array of arrays? 2. Perl Hash of Hashes The following example defines a sample perl hash of hashes. %tgs = ( 'articles' => { 'vim' => '20 awesome articles posted','awk' => '9 awesome articles posted','sed' => '10 awesome articles posted' },'ebooks' => { 'linux 101' => 'Practical Examples to Build a Strong Foundation in Linux','nagios core' => 'Monitor Everything,Be Proactive,and Sleep Well' } ); To access a single element from hash,do the following. print $tgs{'ebooks'}{'linux 101'}; Read more: How do I make a hash of hashes? 3. Hash of Arrays The following example defines a sample perl hash of arrays. %tgs = ( 'top 5' => [ 'Best linux OS','Best System Monitoring','Best Linux Text editors' ],'15 example' => [ 'rpm command','crontab command','Yum command','grep command' ],); To access all elements one by one,do the following. foreach my $key ( keys %tgs ) { print "Articles in group $key are: "; foreach ( @{$tgs{$key}} ) { print $_; } } Read more: How do I make a hash of arrays? 4. Making a Stack Making a stack is very simple in Perl using arrays with push & pop function. First,define an array as shown below. @array = ( 1,2,3,4,5 ); Stack operation: push ( @array,6 ); # pushes the content at the end of array. pop ( @array ); # gives the top element 6. Read more: How do I make a stack? 5. Visualize a Complex Perl Data Structure When you see a code which builds complex data structure,to visualize it better,use Dumper as shown below. use Data::Dumper; print Dumper $ref; The above code snippet will dump the output in a user friendly way as shown below. $VAR1 = { 'a' => [ { 'A' => 1,'B' => 2 },{ 'D' => [ 4,5,6 ],'C' => [ 1,3 ] } ] }; From the above output,you can clearly tell which is array,which is hash,and the dependencies,etc. Read more: How can I visualize my complex data structure?