SAMS Teach Yourself Perl in 24 Hours THIRD EDITION

Simple Patterns

In Perl, patterns are enclosed inside a pattern match operator, which is sometimes represented as m//. A simple pattern might appear as follows:

m/Simon/

The preceding pattern matches the letters S-i-m-o-n in sequence. But where is it looking for Simon? Previously, you learned that the Perl variable $_ is frequently used when Perl needs a default value. Pattern matches occur against $_ unless you tell Perl otherwise (which you'll learn about later). So the preceding pattern looks for S-i-m-o-n in the scalar variable $_.

If the pattern specified by m// is found anywhere in the variable $_, the match operator returns true. Thus, the normal place to see pattern matches is in a conditional expression, as shown here:

 if (m/Piglet/) ...