Thanks Marshall for the valuable input. Your code is crisp and easy to understand. I appreciate the tips provided by you, Corion and Hauke Although I am not able to figure out why it doesnt display the result for the last name from STDIN. In the example shown, the result for last element "john" is missing. 

Input: 
4
tom 332211
harry 112233
ryan 445566
john 334455
jay
harry
ryan
kelly
john

Output:
Not found
harry=112233
ryan=445566
Not found

Code:

use strict;
use warnings;
use Data::Dumper;

my %phone_num;

while (my $line = <STDIN>)
{
   my $name;
   my $phone;
   
   
   next unless ($name, $phone) = $line =~/^\s*([a-zA-Z]+)\s+(\d+)*/; 

   if (defined $phone)  # A new phone book entry
   {
       $phone_num{$name} = $phone;
   }
   else                 # Just a name. 
   {
       if ($phone_num{$name})
       {
           print "$name=$phone_num{$name}\n";
       }
       else
       {
           print "Not found\n";
       }
   }
}

[download]

The reason why I used a for loop inside a for loop was to get the correct value index to properly map name value pairs. Once I spliced the array N, I only have the names which needs to be checked for phonebook entry inside @N. Then I checked @N against the keys of the hash inside @data. Now the index i for @N need not be same for @data, that's why used another for loop to match the correct key-value pairs once the if condition i.e. grep holds good. This kind of approach makes it a lot more cumbersome. Your algo and approach seems to be way better and fast. Thanks!

In reply to Re^2: Perl program to look into the phone directory and in case of a match, print the name along with the number by dk27
in thread Perl program to look into the phone directory and in case of a match, print the name along with the number by dk27

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