Many thanks for your suggestion.
You all are correct, for ease of explanation I did not mention that the inputfile is a XML file.
Basically I have a hash which contains the tags of xml and their default values .
Now only those tags will be replaced which has a key in the hash. So the xml inputfile actually looks like :

**********************************
<user>
<default>dean</default>
</user>
<id>
<default>38339</default>
</id>
<workarea>
<default>/home/dean</deault>
</workare>
************************************

And lets assume the hash has 2 keys for id and workarea :

%hash = (id => 94848, workarea=> '/home/unix' )
So in this case while parsing the xml , I will only replace <default> values for <id> and <workarea>

Hi,
I could do it myself. Here goes the code


tie @array , 'Tie::File' ,  "$file" ;  

    foreach my $key (keys %varHash)
    {
        my $keyflag = 0 ;
        my $changedVal = $varHash{$key}{newVal};
        my $startdef = '<default>';
        my $enddef = '</default>';
        my $storedindex;
        
        print "key $key | changedVal $changedVal \n";
        for(my $i = 0 ; $i <= $#array ; $i++)
        {
            if($array[$i] =~ /$key/)
            {
                print "here $key \n";
                $keyflag = 1 ;
                next;
            }
            elsif ($array[$i] =~ /\<default\>.*?\<\/default\>/gs)

            {
                #    print "array[i] $array[$i] \n";
                if($keyflag)
                {
                    $array[$i] = "$startdef"."$changedVal"."$enddef";
                    $keyflag = 0;
                    last;
                }
            }
            elsif($array[$i] =~ /^\s*\<default>.*[^\>]$/)
            {
                $storedindex = $i ;
            }
            elsif($storedindex > 0 )
            {
                if ($array[$i] =~ /\<\/default\>/)
                {
                    my $range = $i - $storedindex;
                    splice(@array, $storedindex,$range);
                    $array[$storedindex] = "$startdef"."$changedVal"."
+$enddef";
                    last;
                }
            }                
            
        }            
    }

    untie(@array);

}
[download]

... the inputfile is a XML file. ... I could do it myself.

You could, but why not use one of the many good modules for handling XML available on CPAN? XML::Simple, XML::LibXML, XML::Twig... your code could be reduced to a few lines.