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Escape it with a \<br />
<br />
\.<br />
<br />
or put inside a range [.], inside the [] the . dot is literal
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Escape it with a \

\.

or put inside a range [.], inside the [] the . dot is literal

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Rather than<br />
<br />
[a-zA-Z\s0-9.]{0,500}<br />
<br />
You could trye<br />
<br />
[\d\w\s.]{0,500}<br />
<br />
\d, \w and \s &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Shorthand character classes matching digits, word characters, and whitespace. Can be used inside and outside character classes.<br />
<br />
<a href="http://www.regular-expressions.info/reference.html" rel="ugc">http://www.regular-expressions.info/reference.html</a>
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Rather than

[a-zA-Z\s0-9.]{0,500}

You could trye

[\d\w\s.]{0,500}

\d, \w and \s      Shorthand character classes matching digits, word characters, and whitespace. Can be used inside and outside character classes.

http://www.regular-expressions.info/reference.html [http://www.regular-expressions.info/reference.html]

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<div class="content wysiwyg-content">
I have an expression: [a-zA-Z\s0-9]{0,500}, it as long as I don't enter a period character. How do I add a the option for a period character?<br />

<pre><code id="code-308769">&lt;asp:RegularExpressionValidator ID=&quot;revSN&quot; runat=&quot;server&quot; ControlToValidate=&quot;txtSN&quot; ErrorMessage=&quot;Please eneter a vaild information in this field.&quot; ValidationExpression=&quot;[a-zA-Z\s0-9]{0,500}&quot;&gt;&lt;/asp:RegularExpressionValidator&gt;
</code></pre>
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I have an expression: [a-zA-Z\s0-9]{0,500}, it as long as I don't enter a period character. How do I add a the option for a period character?

How do I add a match for a period in a Regular Expression Validator

A regular expression ("regex") is a sequence of characters that define a search pattern, mainly for use in pattern matching with strings, or string matching, i.e. "find and replace"-like operations. Regular expression processors are found in several search engines, search and replace dialogs of several word processors and text editors, and in the command lines of text processing utilities, such as sed and AWK. Many programming languages provide regular expression capabilities, some built-in, for example Perl, JavaScript, Ruby, AWK, and Tcl, and others via a standard library, for example .NET languages, Java, Python and C++ (since C++11). Most other languages offer regular expressions via a library.

Regular Expressions

Web applications are systems that run in browsers that perform functions normally associated with other client-based programs. One of the most commonly used web applications is email; instead of downloading individual emails to a local machine, the data is shown through a website. Other examples of web applications are collaborative systems like a wiki or an online game.