c:\test>572961 9991230061 9991230061 is not found 9991230062 9991230062 is found 9991230063 9991230063 is not found Terminating on signal SIGINT(2) c:\test>perl -wle"printf qq[%03d%03d%04d\n], int( rand 1000 ), int( rand 1000 ), int( rand 10000 ) for 1 .. 1e3" | perl 572961.pl >nul File for area code '000' not found at 572961.pl line 12, line 57. 999 trials of lookup (32.287s total), 32.319ms/trial ##

##

#! perl -slw
use strict;
use Benchmark::Timer;

my $T = new Benchmark::Timer;


while( my $number =  ) {
    chomp $number;
    $T->start( 'lookup' );
    if( my( $area, $subarea, $no ) = $number =~ m[^(\d{3})(\d{3})(\d{4})$] ) {
        open FILE, '<', "./tele/$area" 
            or warn "File for area code '$area' not found" and next;
        seek FILE, ( $subarea - 1 ) * 10002, 0;
        my $mask = ;
        print "$number is ", ( substr $mask, ( $no - 1 ), 1 ) 
            ? 'found' : 'not found';
    }
    else {
        print "Invalid telephone number: $number";
    }
    $T->stop( 'lookup' );
}

$T->report;