Regular Expression Tester

sgtwwilson · April 17th, 2009, 01:50 AM

I have been working through Chapter 8 and wanted to build Regular Expression tester. I wrote the code below and it works well provided there are no backslashes "\" in the expression or test string. I'm a bit of a newbie and it appears like the problem stems from the either the HTML form's treatment, or PHP's treatment, of the escape character; for some reason the form feeds \\ when ever \ is posted by the form. Is there a way to avoid this so that I can use the regular expression shorthand?

Here is the code I am using:

PHP Code:


			
<?php
 // request Reg Exp if none has been provided
 if (!isset($_GET['exp']) || !isset($_GET['test'])) {
     $result = 'Please Enter an Expression and a Test String';
 } else {
//test Reg Exp on String and return results
     extract($_GET);
     if (!preg_match('|' . trim($exp) . '|',$test)){
         $result = 'The test does not meet the expression criteria';
     } else {
         $result = 'This test meets the expression criteria';
     }
 }

 ?>


<html>
 <head>
  <title>Regular Expression Checker</title>
 </head>
 <body>
  <h1>Test Your Regular Expression<h1/>
  <h2> Input you expression and test string:<br/><br/></h2>
  <form action="regexp.php" method="get">
   <table>
    <tr>
    <td>Regular Expression:</td>
    <td><input type="text" name="exp" value="<?php echo (isset($_GET['exp'])) ?  trim($_GET['exp']) : ''; ?>" /></td>
    <td><small>Use preg_match() expression mechanisms;<br/> there is no need to use delimiting characters</small></td>
    </tr><tr>
    <td>Test</td>
    <td><input type="text" name="test" value="<?php echo (isset($_GET['test'])) ? $_GET['test'] : ''; ?>" /></td>
    <td><input type="submit" name="submit" value="Test"></td>
    </table>
   </form>
    <br/><br/>
    <h2>Results:</h2>
    <p> <?php echo $result; ?></p>
 </body>
</html>

sgtwwilson · April 17th, 2009, 05:08 PM

It looks like Im the only one on this forum... its become a diary of sorts. Ok, after spending hours searching the web for help I finally came across the function to fix my problem... the stripslashes() function will pull out the slashes added as escapes. So, some working code if anyone is interested:

PHP Code:


			
<?php
 // request Reg Exp if none has been provided
 if (!isset($_GET['exp']) || !isset($_GET['test'])) {
     $result = 'Please Enter an Expression and a Test String';
 } else {
//test Reg Exp on String and return results
     extract($_GET);
    
     if (!preg_match('|' . stripslashes(trim($exp)) . '|',$test)){
         $result = 'The test does not meet the expression criteria';
     } else {
         $result = 'This test meets the expression criteria';
     }
 }

 ?>


<html>
 <head>
  <title>Regular Expression Checker</title>
 </head>
 <body>
  <h1>Test Your Regular Expression<h1/>
  <h2> Input you expression and test string:<br/><br/></h2>
  <form action="regexp.php" method="get">
   <table>
    <tr>
    <td>Regular Expression:</td>
    <td><input type="text" name="exp" value="<?php echo (isset($_GET['exp'])) ?  stripslashes(trim($_GET['exp'])) : ''; ?>" /></td>
    <td><small>Use preg_match() expression mechanisms;<br/> there is no need to use delimiting characters</small></td>
    </tr><tr>
    <td>Test</td>
    <td><input type="text" name="test" value="<?php echo (isset($_GET['test'])) ? stripslashes($_GET['test']) : ''; ?>" /></td>
    <td><input type="submit" name="submit" value="Test"></td>
    </table>
   </form>
    <br/><br/>
    <h2>Results:</h2>
    <p> <?php echo $result; ?></p>
 </body>
</html>

There are more robust expression checkers out there... but this works in a pinch.

pooch · May 10th, 2009, 11:35 AM

Quote:

Originally Posted by sgtwwilson

It looks like Im the only one on this forum... its become a diary of sorts.

Hey Sgt Wilson. I read your posts, though I may not be of much help at this time, as I truly am a beginner. I do have some experience with Perl, so am not a total newb regarding programming.
Anyway, thanks for the posts, and the code fixes. People like me need people like you to work through this stuff. I really need to learn this language. Keep up the good work!
Pooch