Perl invokes a powerful tool for pattern matching that
gives the program great flexibility in controlling matches.
In Perl, a string is matched by placing it between two
slashes as follows:
Thus, /eric/ matches for the string "eric". You may also
match according to whole classes of characters using the
square brackets (). The pattern match will then match
against any of the characters in the class. For example, to
match for any single even numbered digit, you could use
the following match:
For classes including an entire range of characters, you
may use the dash (-) to represent the list. Thus, the
following matches any single lower case letter in the
Likewise, you may use the caret (^) character within the
square brackets to match every character that is "not"
in the class. The following matches any single character
that is not a digit.