7 Components: the Function Pages - Developers

You can also make a search take into account differences in orthography
is well, as in:
neighb(o|ou)r(s)
which effects a search for the American “neighbor” as well as the
British “neighbour” in singular and plural.
The real advantage to regular expressions is that you not only can
look for words, but also letter patterns. For instance, you can use
them to search for email addresses or telephone numbers in TWiki.
The basic unit of such patterns is information on permissible letters:
Expression Significance
[acf] One of the letters indicated.
[a-g] A letter between (and including) a and g.
[^a] All letters except the one indicated.
. any character.
[\-] The minus sign. The backslash functions as a
mask, indicating that the following character is
not a function (as in the normal function of a
backslash as an area sign).
Instead of letters, you can also use numbers or other characters. If
such characters have a special function in RegEx, you must “disarm”
them with a preceding backslash. Then, for instance, you can search
for links to films and audio files in TWiki:
\.mp[g3]
It gets even more interesting when you can also indicate how often a
certain character pattern may occur in a row:
Character Frequency
* Never, once or more than once
+ At least once
? At most once
{n} Exactly n times
{n,} At least n times
{n,m} Between n and m times
The characters indicated are placed behind the expression whose
size is to be determined. Now we can express a search for singular
and plural words in the following way:
Letter patterns
Tab. 13.2
Determine
frequency
Tab. 13.3
13.3 Searching with Regular Expressions �
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