#!/lusr/bin/perl

use warnings;
use strict;


#------------------------------------------------------------------
#variable =~ m/regular_expression/ 
#------------------------------------------------------------------
my $str = "My phone number is 123-4567. This is my home phone.";
if( $str =~ /\d{3}-\d{4}/ ){
   print "There is a phone number in the string:\n\t'$str'\n";
}else{
   print "There is not a phone number in the string:\n\t'$str'\n";
}





#------------------------------------------------------------------
#$& - contains the matching substring 
#$` - contains the substring on the left of the match 
#$' - contains the substring on the right of the match 
#------------------------------------------------------------------
$str = "My phone number is 123-4567. This is my home phone.";
if( $str =~ /\d{3}-\d{4}/ ){
   print "There is a phone number in the string:\n\t'$str'\n";
   print "The phone is: $&\n";
   print "      Before: '$`'\n";
   print "       After: '$''\n";
}else{
   print "There is not a phone number in the string:\n\t'$str'\n";
}




#-----------------------------------------------------------------
$str = "My phones: 123-4567 (home), 234-5678 (office), 345-6789 (cell).";
while( $str =~ /\d{3}-\d{4}/ ){
   print "The phone is: $&\n";
   $str = $';
}




#-----------------------------------------------------------------

$str = "My phones: 123-4567 (home), 234-5678 (office), 345-6789 (cell).";
my @phones = $str =~ /\d{3}-\d{4}/g;
foreach my $phone (@phones){
   print "$phone\n";
}





#-----------------------------------------------------------------
#Getting information about a match
#-----------------------------------------------------------------
my $today = "10/16/2006";
#my $today = "10-16-2006";
if( $today =~ /\b(1[0-2]|0?[1-9])[\-\/](0?[1-9]|[12][0-9]|3[01])[\-\/]((19|20)\d{2})/ ){
   print "Date: $&\n";
   print "Month: $1\n";
   print "Day: $2\n";
   print "Year: $3\n";
   print "Century: ", $4 + 1, "\n";
}





#-----------------------------------------------------------------
#String replacement
#-----------------------------------------------------------------
my $card = "1234 56789012-3456";
if( $card =~ /(\d\d\d\d)[\-\s]?(\d\d\d\d)[\-\s]?(\d\d\d\d)[\-\s]?(\d\d\d\d)/ ){
   	$card = "$1-$2-$3-$4";
}else{
  	$card = "Invalid credit card number!";
}
print "$card\n";




#-----------------------------------------------------------------

$card = "1234 56789012-3456";
if( $card =~ s/\d{4}/****/ ){
   print "$card\n";
}else{
   print "Sorry, there is no match\n";
}




#-----------------------------------------------------------------

$card = "1234 56789012-3456";
$card =~ s/(\d\d\d\d)[\-\s]?/$1-/g; # separate 4-digit groups with dashes
$card =~ s/-$//;                    # remove the trailing dash
$card =~ s/\d{4}-/****-/g;          # substitute 4-digit groups with 4 stars
print "$card\n";