Re: Longest prefix match

[Mihir Kamdar]

I can't recommend reinventing the wheel, I would use the module to
> lookup the country name and the use hash where the country name is the
> key and the rate is the value to get the value, but if you are dead
> set on not using the module your best bet is something like this:
>
> #!/usr/bin/perl
>
> use strict;
> use warnings;
>
> my %prefix_to_rate = (
>         12   => 0.30,
>         1234 => 0.35,
>         134  => 0.50,
>         44   => 0.70
> );
>
> #if there are more than about 50 country codes
> #get rid of the sort and implement min and max
> #in Perl, otherwise sort is actually faster
> my ($shortest, $longest) =
>         (sort { $a <=> $b } map {length} keys %prefix_to_rate)[0, -1];
>
> while (<DATA>) {
>         my ($num, $min) = split;
>         my $rate;
>         for my $len (reverse $shortest .. $longest) {
>                 my $key = substr $num, 1, $len;
>                 last if $rate = $prefix_to_rate{$key};
>         }
>         if (defined $rate) {
>                 print "the rate for $num is $rate: ", $rate * $min, "\n";
>         } else {
>                 print "$num does not have a rate\n";
>         }
> }
>
> __DATA__
> +12555 10
> +44555 20
> +12345 30
> +55555 55
>

Hi,

I tried to implement the way Chas suggested, but am getting a lot of errors.
Plz check my mistakes:-

#!/usr/bin/perl

use strict;
use warnings;

my $file_path =
'/home/user71/RangerDatasource/Customization/TelekomMalaysia/Scripts/Tests/cprogs/files/ratetest';
my %prefix_to_rate = (
       '+12'   =>0.30,
       '+1234' =>0.35,
       '+134'  =>0.50,
       '+44'   =>0.70
);
my %times ;

my ($shortest, $longest) =
                   (sort { $a <=> $b } map {length} keys %prefix_to_rate)[0,
-1];

my $continue  = 1;

$SIG{INT} = $SIG{TERM} = sub { $continue = 0 };

while ($continue) {
opendir my $dh, $file_path or die $!;
        while (my $file = readdir $dh) {
                my $fname = "$file_path/$file" ;
                next unless -f $fname;
                unless (exists $times{$file}){
                        my $line;
                        open (my $IN_FILE,"<","$file_path/$file") or die
$!." file not found" ;


            while ($line=readline($IN_FILE))
            {
                my @cdr=split (/,/, $line) ;
                ($cdr[3],my $min) = split;
                my $rate;
                for my $len (reverse $shortest .. $longest) {
                    my $key = substr $cdr[3], 1, $len;
                    last if $rate = $prefix_to_rate{$key};
            }

        if (defined $rate) {
            print "the rate for $cdr[3] is $rate: ", $rate * $min, "\n";
            }
            else
            {
                print "$cdr[3] does not have a rate\n";
            }
        }
    }
}
closedir $dh ;
}


Thanks,
Mihir