Double-quoted strings can interpolate other variables inside.
my $name = "Inigo Montoya";
my $relative = "father";
print "My name is $name, you killed my $relative";
If you don't want interpolation, use single-quotes:
print 'You may have won $1,000,000';
Or you can escape the special characters (sigils):
print "You may have won \$1,000,000";
This email address won't be what you want it to be:
my $email = "andy@foo.com";
print $email;
# Prints "andy.com"
The problem is that
@foo is interpolated as an array. This problem is obvious if you have
use warnings turned on:
$ perl foo.pl
Possible unintended interpolation of @foo in string at foo line 1.
andy.com
The solution is either to use non-interpolating quotes:
my $email = 'andy@foo.com';
my $email = q{andy@foo.com};
or escape the
@
my $email = "andy\@foo.com";
A good color-coding editor will help you prevent this problem in the first place.
my $str = "Chicago Perl Mongers";
print length( $str ); # 20
substr() does all kinds of cool string extraction.
my $x = "Chicago Perl Mongers";
print substr( $x, 0, 4 ); # Chic
print substr( $x, 13 ); # Mongers
print substr( $x, -4 ); # gers
Unlike other languages, Perl doesn't know a "string" from a "number". It will do its best to DTRT.
my $phone = "312-588-2300";
my $exchange = substr( $phone, 4, 3 ); # 588
print sqrt( $exchange ); # 24.2487113059643
You can increment a string with
++. The string
"abc" incremented becomes
"abd".
$ cat foo.pl
$a = 'abc'; $a = $a + 1;
$b = 'abc'; $b += 1;
$c = 'abc'; $c++;
print join ", ", ( $a, $b, $c );
$ perl -l foo.pl
1, 1, abd
Note that you must use the
++ operator. In the other two cases above, the string
"abc" is converted to
0 and then incremented.
You can create long strings with
Heredocs are
- Allows unbroken text until the next marker
- Interpolated unless marker is in single quotes
my $page = <<HERE;
<html>
<head><title>$title</title></head>
<body>This is a page.</body>
</html>
HERE
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