什么阻止用户在POST中发送它们之前编辑php变量？

Question

For security reasons, I'm trying to learn more about how PHP stores variables. PHP is a server side language, yes, but I imagine when someone is editting a php variable it stays on the local machine before being sent in POST. So if I set a variable in my PHP code ($foo = "bar"), and want it to submit it in a later mysqli query, what stops someone from changing $foo to a different string value using some kind of external program before being later submitted? How would I stop this if that is the case?

Answer 1

In order to stop someone from changing the variable you can change the variable $foo = "bar" to constant variable as ( const $foo = "bar" ). For more explanation go to the link below http://php.net/manual/en/function.constant.php