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URGENT: Easy Regex Question

Posted on 2004-04-07
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Last Modified: 2010-04-15
I'm missing something here,  I only want to allow alphanumeric characters and the period.  i have the following code

Regex regex = new Regex("[^[a-z][A-Z][0-9].]");
if(regex.IsMatch(txtName.Text) == true)

Do I need a carrot before each of those sub groups?  

(the code is not working properly).
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Question by:jjacksn
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3 Comments
 
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Expert Comment

by:eric_duncan
ID: 10780716
Try this instead, it should do what you want:

Regex regex = new Regex("^[a-zA-Z0-9.]+$");


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Accepted Solution

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eric_duncan earned 500 total points
ID: 10780781
To explain further, tou need to group all of the characters you are looking for into a single group rather than creating three consecutive groups because the regex parser will process this as looking for 3 consecutive characters rather than a single character that is a member of all three groups.

In plain english, your old regex does this:

First, match any character not in "[a-z",
followed by any character in "A-Z",
followed by any character in "0-9",
followed by any character,
followed by ].

The new one supplied above does this:

First, start at the beginning of the string,
then match any character in "a-zA-Z0-9." and continue doing this until the end of the string is reached.

Does this help?

Eric
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LVL 48

Expert Comment

by:AlexFM
ID: 10780886
Regex regex = new Regex("[a-zA-Z0-9.]+");
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