RegEx.DLL

RegEx.DLL provides some much needed regular-expression handling for VB programmers. The 'clsRegEx' class implements all the common UNIX wildcard characters allowing sophisticated string comparisons and search-and-replace operations to be performed.

* The '*' character represents zero or more occurrences of the previous character in the expression:

ab*c matches ac, abc, abbc, abbbbbbbc ...

* The '+' character represents one or more occurrences of the previous character in the expression:

ab+c matches abc, abbc, abbbbbbbc but not ac

* Numbers within curly brackets represent a specific number of occurrences of the previous character:

a{3} matches aaa a{3, 5} matches aaa, aaaa and aaaaa

* The '?' character represents zero or one occurrences of the previous character:

a?c matches ac and aac

* The '.' character represents any single character:

a.c matches abc, aXc but not ac or abbc

Round brackets can be used to apply multipliers, such as '*' or '+', to groups of characters:

* (abc)* matches an empty string, abc, abcabc, abcabcabc ...

* (abc)+ matches abc, abcabc, abcabcabc ...

Square brackets can be used to specify possible values for a single character. A hyphen can be used in this context to represent a range of characters. If the first character within the brackets is a '^' then the range is exclusive rather than inclusive (ie. the expression matches any single character not shown):

* a[bB]c matches abc and aBc

* a[^0-9]c matches abc and aXc but not a0c ... a9c

A '\' symbol negates the special meaning of the following character. Only valid if it precedes one of *+?\{([])}.

* a\*c matches a*c

* a[\[\]]c matches a]c and a[c

* a\\c matches a\c

* ab\c is not a valid expression

The download includes VB code samples demonstrating how to use the library.

This library is still in beta test - it works well for short expressions, but due to the recursive nature of the code longer strings can take a while.