Quicky security question

[Vimi]

I've written a script where people can input a number to see specific random results. Would there be any potential issues with someone inserting code into the field?

It's pretty much used like this:

$num = $_POST['a'];
srand($num);
echo $num;

[Mittineague]

Nothing serious that I can think of unless there's a way to enter PHP code into it and have the results output. eg. ??? -- not that it would work, but you get the idea.
$_POST['a'] = "0);phpinfo();("

IMHO, it would be prudent and good habit to always validate. If it's only numbers allowed you could use trim() and is_numeric() at the least.

[AnthonySterling]

In addition to Mittineague's excellent advice, you should also cast the variable at an Integer.

<?php
$num = (Integer)$_POST['a'];
srand($num);
echo $num;
?>

[Vimi]

Thank you both! I'll be sure to do that