Hi megaurav2002, if I understood your question correctly then the following would will help you.

use strict;
use warnings;

my @array = qw(id_1_1 id_2);

for (@array){
    print "$1\n" if (m/id\_(\d+)(?!\_)/);
}

__END__
Output:
------
2
[download]

Also look into How (Not) To Ask A Question