Help with a regular expression.

I have a regular expression used for input to a textbox control
Hello, I need help understanding a regular expression. (There are two parts to my question.) Here is my regular expression:
I interpret it to ensure the following constraints:
1.) alphanumeric characters only a-z and A-z
2.) Max 1-40 characters
Now what does the ^ character stand for, and the .\s

That is part 1 of my question.

Part 2,
Please modify the regular expression to prevent blank characters. This might be tricky. You see I need to prevent the user from entering nothing into a text box, or just blank spaces.  (Note for various reasons, I am not allowed to use a required field validator control)

Who is Participating?
also try:

<asp:RegularExpressionValidator ID="RegularExpressionValidator4" runat="server" ControlToValidate="txtField" ErrorMessage="Letters Only" ValidationExpression="[a-zA-Z]{1,40}">

Change ControlToValidate to whatever field you need validated upon.
Change ErrorMessage to anything you want

and as far as the expression goes change {1, 40}  to the boundary you want to enforce (40 being max), setting it from {1, 40} to {1, +} should allow for unlimited chars if needed.
ValidationExpression = ereg('[^A-Za-z]'), {1, 40};

$textfield = $_POST['txtTextField'];

if(ValidExpression($name) && (!empy($textfield))
  // run the rest of the script

Hope this helps
brgdotnetcontractorAuthor Commented:
Hello Seraph. I think there is a big break down in communication here. I wanted to know how to interpret the validation expression I posted. Specifically the characters ^, and  .\s

Part 2 was how to prevent entry of blank characters.

Your reply is confusing. I don't understand what you are telling me?

^ indicates the Beginning of line or string
\s indicates end of line string, space or white space
Question has a verified solution.

Are you are experiencing a similar issue? Get a personalized answer when you ask a related question.

Have a better answer? Share it in a comment.

All Courses

From novice to tech pro — start learning today.