Character Classes << Matching/Replacing >> Functions - Intro
As seen on the previous tutorial pages, ereg( ) and eregi( ) are used to find patterns. Taking this to the next level will allow you to find a pattern and replace it with a new value. This is using ereg_replace( ) and eregi_replace( ). The i has the same effect as before, case insensitive.

The replace command looks like this :

Very similar to the normal eregi command only it has an extra parameter in the middle.

A replacement can be used for many different uses such as...
1. Taking an entered URL and making it a clickable one.
2. Replacing a text smilie into an image one.
3. Replacing bad words with *@!%.

Most of these examples would be taking some user input from a form and processing it to a webpage or email. We'll do an example using the smilies.

On the form page
<form method="post" action="changeit.php">
<input type="text" name="entry">
<input type="submit" value="submit">

$pattern = ":\)";
$replacement = "<img src=\"smilie.gif\">";
$entry = ereg_replace($pattern,$replacement,$entry);
echo "$entry";

Here is the test in action. If you enter :) into the text box, it will appear as a smilie image in the second cell. The current page will reload upon submit, so you will have to scroll down to see the result here.

Fatal error: Uncaught Error: Call to undefined function ereg_replace() in /misc/40/000/085/738/8/user/web/ Stack trace: #0 {main} thrown in /misc/40/000/085/738/8/user/web/ on line 63