1 ================================================================================
2 
3                                    Scalars
4 
5   A scalar can store a string, number, reference (which points to another
6   variable), or a file handle (which lets you read and write to a file).
7 
8 	my $server = "irc.example.com";
9 	my $port = 6667;
10 
11   The first scalar $server contains the string "irc.example.com". A string
12   is made up of letters. The second scalar $port contains the number 6667.
13 
14 ================================================================================
15 
16                                    Strings
17 
18   If you want to use a literal string, make sure to put it around 'single
19   quotes' or "double quotes" -- if you do not, perl will report an error:
20 
21 	print Welcome to my IRC channel;
22 
23 	syntax error at - line 1, near "my IRC channel"
24 	Execution of - aborted due to compilation errors.
25 
26   When you use "double quotes", perl will evaluate any variables inside the
27   string and replace them with their values.
28 
29 	my $nick = "perlmonk";
30 	my $msg = "Welcome to the channel, $nick!";
31 
32   The perl interpreter replaces $nick with the string "perlmonk", so that
33   $msg will contain the string "Welcome to the channel, perlmonk!" This
34   is called *string interpolation*.
35 
36   When you use 'single quotes', no string interpolation takes place. The
37   string is identical to what you type.
38 
39 	my $msg = 'Welcome to the channel, $nick!';
40 
41   The scalar $msg will literally contain 'Welcome to the channel, $nick!'
42   and not 'Welcome to the channel, perlmonk!' This can be useful to
43   avoid accidental string interpolation:
44 
45 	my $msg = 'Just call $mrmoney and send an email to @cash.com!';
46 
47   If we had used double quotes above, perl would try to replace $mrmoney
48   and @cash with the value of those variables. We use single quotes
49   to keep them literal.
50 
51   If you need to start a new line in your string, you can use "\n":
52 
53 	print "To start, press any key.\nWhere's the 'Any' key?"
54 
55   This will print:
56 
57 	To start, press any key.
58 	Where's the 'Any' key?
59 
60 ================================================================================
61 
62                                     Numbers
63 
64   There are two number types: integers and floats. An integer is a number
65   with no decimals or fractions. A float is stored as a decimal or fraction.
66 
67 	my $port = 6697;
68 	my $delay = 3.5;
69 
70   $port is the integer 6697 but $delay might last for three and a half
71   seconds.
72 
73 ================================================================================
74 
75                                    References
76 
77   A reference points to another variable, like a pointer in C. The reference
78   does not store the data itself, but stores the address for the data you want.
79 
80 	my $channel = "#perl102";
81 	my $channel_ref = \$channel;
82 
83   $channel_ref now points to $channel, but does not contain the string
84   "#perl102" itself.
85 
86   To get the value of this reference, put an extra $ in front of the
87   reference:
88 
89 	print "Welcome to $$channel_ref, new user!\n";
90 
91   References may not seem very useful now, but we will use them frequently
92   when programming in Perl.
93 
94 ================================================================================
95 
96                                   Filehandles
97 
98   We can call open and pass it a scalar and a filename to open a file:
99 
100 	open(my $filehandle, '>log.txt');
101 
102   The greater than > sign means we want to redirect output to log.txt.
103   Perl will store the handle to the file in the scalar. We can then print
104   to $filehandle to write to the text file:
105 
106 	print $filehandle "12:56 -!- nickname [nick@10.0.0.1] has joined #channel";
107 	print $filehandle "21:28 -!- mode/#channel [+o nickname] by you";
108 	close($filehandle);
109 
110   Once you are done with a filehandle, make sure to close it. We now have IRC
111   logs written to log.txt which we can read later.
112 
113 ================================================================================
114 
115                              Learn more about Perl
116 
117   At any time, you can get more information by using perldoc:
118 
119   $ perldoc perldoc
120 
121   Websites to learn more about Perl:
122 
123   http://learn.perl.org
124 
125   http://www.perldoc.com
126 
127 ================================================================================
128 
129                                 Auto Greet Bot
130 
131   Open up ~/secondbot and follow the instructions to set up your second bot.
132 
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