Apostrophe issue

I have built a search engine using php and mysql.

Problem: When I submit a word with an apostrophe in it and return the value to the text field using $_GET the apostrophe has been replaced with a backslash and all characters after the apostrophe are missing.

Example: Submitted Words: Just can't get enough
Returned Value (Using $_GET): Just can\
Also the url comes up like this:search=just+can%27t+get+enough

As you can see the ' has been replaced with a \ and get enough is missing.

Question: Does anybody know what causes this to happen and what is the solution to fix this problem?

The code: http://tinypaste.com/11d62

Solution

From your description of "value to the text field" I speculate you have some output code like this:

 Redisplay
 <input value='<?=$_GET['search']?>'>

In that case the contained single quote will terminate the html attribute. And anything behind the single quote is simply garbage to the browser. In this case applying htmlspecialchars to the output helps.

(The backslash is likely due to magic_quotes or mysql_*_escape before outputting the text. I doubt the question describes a database error here.)

Update: It seems it's indeed an output problem here:

  echo "<a href='searchmusic.php?search=$search&s=$next'>Next</a>";

Regardless of if you use single or double quotes you would need:

  echo "<a href='searchmusic.php?search="
      . htmlspecialchars(stripslashes($search))
      . "&s=$next'>Next</a>";

(Notice that using stripslashes is a workaround here. You should preserve the original search text, or disable the magic_quotes rather.)

Okay I forgot something crucial. htmlspecialchars needs the ENT_QUOTES parameter - always, and in your case particularly:

// prepare for later output:
$search = $_GET['search'];
$html_search = htmlspecialchars(stripslashes($search), ENT_QUOTES);

And then use that whereever you wanted to display $search before:

  echo "<a href='searchmusic.php?search=$html_search&s=$next'>Next</a>";