I am wanting to literally take the HTML form input with the ID "bet" and after the value has been entered and submitted; get the exact input for example: '100' may be entered, as I am wanting to perform an if statement to check that the value submitted isn't less than 0 for obvious reasons so then I can stop the webpage proceeding to perform the bet, and make the user instead enter a valid amount.
The code that I am having an issue with is below, upon loading the page I am getting the error: Notice: Undefined index: bet
<form action="duel.php" name="duel" id="duel">
<input type="text" id="betamount" name="betamount">
<?php
$data = $_GET['betamount'];
echo $data;
?>
</form>
I am fairly new to programming in PHP, so any help would be greatly appreciated.