Which regular expression should I use to validate weight in VB? : <p>In one of my program's procedures; I want to use a regular expression along with a match statement, to make sure that the user properly input's the weight of an individual into a  text box and also to make sure that it is entered in the right format. But I don't know which one to implement and am not very experienced with using the RegEx class in VB.Net.</p>

<p>However, I know that the regex which is used must make sure that the user has entered the information in the following format:</p>

<p><strong><em>123lb or 122223lb or 987LB or 23lB</em></strong></p>

<p>The number of digits used before the 'lb' does not matter but the 'lb' section must be case-insensitive. The RegEx must also look for no other letters apart from "lb".</p>

<p>For instance, some examples that shouldn't be matched:</p>

<ul>
<li>lb123 (The lb has to come after the digits)</li>
<li>ab987 (The only letters that should be matched are lb)</li>
<li>4875638546cder (Here the number of digits are fine, but the letters aren't just lb)</li>
</ul>

<p>Therefore in summary, the regex must:</p>

<ul>
<li>Look for no letters other than 'lb'</li>
<li>Make sure that 'lb' comes after the digits entered by the user</li>
<li>Be case-insensitive</li>
</ul>

<p>Any help would be much appreciated!</p>

<p>Thanks for reading and have a good day!</p>
