Differeing PHP code behaviors

Question

My PHP -- specifically an elseif statement -- does not behave the same way on AL2 as it does on my CentOS 7 dev server.  Both systems are supposed to be running PHP v7.3.  I will note the AL2 system does not have the php-tidy module installed, and I am having GREAT difficulty adding it; but, I do not know if that has anything to do with the problem.  What would cause an if->elseif->else statement to perform one way on CentOS 7 and differently on AL2?  BTW, it would appear that PHP on the AL2 system is dropping the last '->else' part.  Also if I code the elseif part to be precisely $var === 1, it drops the 'elseif' part of the statement and does the else statement.

```
if($var > 1) {
  // echo HTML form stuff
}elseif($var == 1) {
  // echo HTML table header  code only (no form elements)
  // There is an '&' in the text to be echoed
}else{
  // echo different HTML table header code, again no form elements
  // There is a '/' in this text to be echoed
}
```
I'm not the best coder, but this code works PERFECTLY on CentOS 7, running PHP v7.3.33 (with the php-tidy module enabled.)  Any guidance you all could provide would be greatly appreciated.

Accepted Answer

You'd need to debug value of `$var` on both setups and compare it. It's obvious that it will be different, and then based on result you can try to understand the root cause of difference. The simplest way to debug is to add `var_dump($var);` before that `if-elseif-else` statement.

Answer

IMO the root cause of your issue will be the use of the "Equal" comparator. PHP is a loosely typed language and using `==` (Equal) instead of `===` (Identical) allows PHP to automatically cast either value before making the comparison.  This effect is compounded when a value is `0` or `1` because they will be interchanged with `TRUE` & `FALSE` so your initial intention to verify that the value of `$var` is `"1"` will become "is there a value in `$var`?"

You can read more about [Comparison Operators](https://www.php.net/manual/en/language.operators.comparison.php) on the PHP docs.

In a case where you are using two different Operating Systems, I would imagine you are dealing with different default PHP [Runtime Configurations](https://www.php.net/manual/en/configuration.php).  To verify this you can export the current configuration from each instance using the [phpinfo()](https://www.php.net/manual/en/function.phpinfo.php) function and perform a Diff.

BTW, don't leave the function accessible for longer than you need it as this is a security risk.

Differeing PHP code behaviors

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