Published: Wednesday, March 15, 2000
Utilizing Regular Expressions, Part 3
Read Part 2
Read Part 1
In
Part 2 we discussed how to use regular expressions
to match character classes and pattern repetition. In this part, we'll look at the
Replace method of the
RegExp object and some finish the article
off with a discussion on some of the more advanced uses of regular expressions.
The Replace Method
If you're new to regular expressions, chances are you've always relied on the standard
VBScript Replace function to replace certain substrings with other
substrings. While the Replace function is easy to use, it lacks the power
offered by the Replace method of the regular expression object. For example,
imagine that you wanted to replace a number of offensive words in a string with
less offensive variations. As we discussed earlier in this article, using the Replace
function can lead to some headaches. For example, if we wished to replace all instances
of "hell" with "heck" using the Replace function, we'd blindly turn
"Hello" into "Hecko".
Using regular expressions, however, we can search for the word "hell" by using the
special word boundary symbol. The following code snippet will replace particular
words with other words (and can easily be adapted to provide a censorship type
system on your site):
Dim str ' some string that needs to have certain words
' replaced with other words
Dim objRegExp
Set objRegExp = New RegExp
objRegExp.IgnoreCase = True
objRegExp.Global = True
'Replace all instances of Apache with IIS
objRegExp.Pattern = "\bApache\b"
str = objRegExp.Replace(str, "IIS")
'Repalce all instances of Perl with ASP
objRegExp.Pattern = "\bPerl\b"
str = objRegExp.Replace(str, "ASP")
Set objRegExp = Nothing 'Clean up!
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Note that the Replace method takes two parameters: the first is the
string to search; the second is the text to replace any matches with. The Replace
method returns the modified string.
Advanced Uses of Regular Expressions
One of the best uses of regular expressions is for server-side form validation.
I have not been able to find many articles on server-side form validation using
regular expression using VBScript. Those only article I found was one here on 4Guys:
I did, however, find a number of articles on client-side validation with regular expression and
server-side validation with regular expression.
There are, of course, other uses for regular expression. If you have some good, practical uses
of regular expression, and would like to share them with the 4Guys audience, please
send me your ideas!
Happy Programming!
Read Part 2
Read Part 1
