How can i check if user changed post value? - php

Question

I have a form for users to give reputations to people.
I'm trying to check if user changed select value to cheat by giving more points
Here is my system:
There is a select box where users can choose how many reputation to give to the user, I'm using the following code to check if user changed the values by inspecting the element:
// Validate post
if(trim($_POST["reputationToGive"]) === 1){
$added = 1;
} elseif(trim($_POST["reputationToGive"]) === 2){
$added = 2;
} elseif(trim($_POST["reputationToGive"]) === 3){
$added = 3;
} else {
// fallback event
}
Code I'm using for select box:
<option value='1'>Give 1 reputation</option>
But somehow, it always triggers the fallback event.
Looking for corrections, have a great day!

Answer 1

I guess the === gives you the problem.
I don't know how you wrote the selectbox. But my geuss is that you get strings back and compare it to integers. Also trim will convert it to string.
I also suggest using a switch for this.
$value = (int) trim($_POST["reputationToGive"]);
$added = 0;
switch ( $value ) {
case 1:
case 2:
case 3:
$added = $value;
break;
default:
// fallback event
break;
}
If you want to be sure the answer is not changed in the post. You could use totally different values in the form that you will translate to the right value in the script.
$value = trim($_POST["reputationToGive"]);
$added = 0;
switch ( $value ) {
case 'AD3ZY':
$added = 1;
break;
case 'B&7X1':
$added = 2;
break;
case 'Px!29':
$added = 3;
break;
default:
// fallback event
break;
}