Game Development Reference
In-Depth Information
Character Class
A character class is used to represent a set of characters and can be any of the following:
x
: Represents the character
x
itself, not one of the magic characters
^
,
$
,
()
,
%
,
.
,
[
,
]
,
*
,
+
,
−
, or
?
.
: Functions in same way as the wildcard that represents all characters
%a
: Represents all letters
%c
: Represents all control characters
%d
: Represents all digits
%l
: Represents all letters (lowercase)
%p
: Represents all punctuation characters
%s
: Represents all space characters
%u
: Represents all uppercase characters
%w
: Represents all alphanumeric characters
%x
: Represents all hexadecimal characters
%z
: Represents the character with the representation 0
%
x
: Allows you to escape any magic character (note that
x
is not the literal
character
x
, but any nonalphanumeric character)
[
set
]
: Represents a union of all characters in
set
. The range of characters can
be specified with a hyphen (−), as in
[0-9]
or
[a-z]
.
[^
set
]
: Represents the complement of
set
. So,
[^0-9]
would mean all
characters that are not in the range 0 to 9.
For all classes that are represented by a single letter (e.g.,
%a
,
%c
,
%s
, and so on), the corresponding
uppercase letter represents the complement of the class. So,
%S
represents all non-space characters.
Pattern Item
A pattern item is a single character class that matches any single character in the class.
There are a few characters that help quantify the matches:
*
: This matches zero or more repetitions of characters in the class. This will
always return the longest possible sequence.
+
: This matches one or more repetitions of characters in the class. This will
return the longest possible sequence.
—
: This also matches zero or more repetitions of characters in the class, but
unlike
*
, this will match the shortest possible sequence.
?
: This will match zero or one occurrence of a character in the class.
