Chat Application using PHP; Code Correction

I am making an online chat application for my school. I thought it would be cool for users t开发者_StackOverflow中文版o just switch between users from the same iframe, the box I used that displays msg.txt. Well, it occurred to me that I could just make a form in html, and in php, have an if...else statement concerning the form, basically stating that "If word is received by the 'Aaron' form, Then switch $msg to $msg1." However, it didn't work. What did I do wrong? The code is displayed in a link. The following is a small section of my code, the code I am focused on for this specific problem. http://key-mail.zxq.net/sourcecode.txt

By the way, it was giving me an error having something to do with a T_STRING. What is that? I've searched the web and I can't quite figure it out. Of course, I know what a string is, but I don't know what a T_STRING is or what the T stands for.

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You are not escaping your output. Instead of:

die(" ...

Do:

$html = <<<EOA
___ YOUR HTML GOES HERE
EOA;
die($html);