Appendix A. Answers to Exercises - Perl Cd Bookshelf [Electronic resources] نسخه متنی

Appendix A. Answers to Exercises

Contents:

Answers for Chapter 2

Answers for Chapter 3

Answers for Chapter 4

Answers for Chapter 5

Answer for Chapter 6

Answers for Chapter 7

Answers for Chapter 8

Answer for Chapter 9

Answer for Chapter 10

Answer for Chapter 11

Answer for Chapter 12

Answers for Chapters 13-15

This appendix contains the answers to the exercises presented
throughout the book.

A.1. Answers for Chapter 2

Here''s one way to do it. First, start with the
package directive and use
strict:

package Oogaboogoo::date;
use strict;

Then define the constant arrays to hold the mappings for day-of-week
and month names:

my @day = qw(ark dip wap sen pop sep kir);
my @mon = qw(diz pod bod rod sip wax lin sen kun fiz nap dep);

Next, define the subroutine for day-of-week-number to name. Note that
this subroutine will be accessible as
Ooogaboogoo::date::day:

sub day {
my $num = shift @_;
die "$num is not a valid day number"
unless $num >= 0 and $num <= 6;
$day[$num];
}

Similarly, you have the subroutine for the month-of-year-number to
name:

sub mon {
my $num = shift @_;
die "$num is not a valid month number"
unless $num >= 0 and $num <= 11;
$mon[$num];
}

Finally, the mandatory true value at the end of the package:

1;

Name this file date.pl within a directory of
Oogaboogoo in one of the directories given in your
@INC variable, such as the current directory.

Section 2.10.2)

Here''s one way to do it. Pull in the
.pl file from a place in your
@INC path:

use strict;
require ''Oogaboogoo/date.pl'';

Then get the information for the current time:

my($sec, $min, $hour, $mday, $mon, $year, $wday) = localtime;

Then use the newly defined subroutines for the conversions:

my $day_name = Oogaboogoo::date::day($wday);
my $mon_name = Oogaboogoo::date::mon($mon);

The year number is offset by 1900 for historical purposes, so you
need to fix that:

$year += 1900;

Finally, it''s time for the output:

print "Today is $day_name, $mon_name $mday, $year.\n";