PHP error when host changes

Question

Good afternoon, I used an online host with php 7 and I had the following syntax

if(!saber_se_não_existe) {}

It always worked as well as this

if(saber_se_existe) {}

So much so that I rediscovered my entire code replacing EMPTY and ISSET with this one that got show but today I went to run in PHP localhost and this does not work, I had to change everything to ! Empty or Empty and PHP is also 7, what allows this is some extension? if yes, can you tell me which one? i on localhost used PHPDESKTOP both 47 and 53 give the same error but online no.

Edit

I have an IF condition that checks if a variable was set that in this case is used isset and to know if Empty is empty, ie

$existe = true;
$nao_existe = false;

Soon

if(empty($existe)) {
// não mostra pois existe
}

and

if(isset($nao_existe)) {
// mostra pois existe, mesmo estando vazia
}

as well as I can use the

unset(variavel_com_ou_sem_valor);
$varialvel_com_ou_sem_valor ? false : true;

there are many ways to do it, so much so that I discovered the example from above, that it is enough to do

if($variavel_com_ou_sem_valor) {
// se tem mostra
}

and

if(!$variavel_com_ou_sem_valor) {
// se não tem mostra
}

only this, however, my online server, both in an android emuloader and an internernet Shared, work the latter, but on my localhost with PHPDESKTOP of

Undefined index

Answer 1

Your environments are with different configurations of error reporting.

If you look at the php.ini or phpinfo() of each, you will see two settings:

error_reporting = E_ALL # ou outro valor
display_errors = true # ou false

The combination of possible values in these two settings causes some servers to complain about more aspects of their code than others. If you change the values to be the same, you will see the same errors in both environments (as long as it is the same version of PHP).

In your specific case one of the environments is reporting that one (or more) of the variables tested was not previously declared (undefined index, índice não declarado), which is a good practice but is not mandatory. This is not a defect (hence the level NOTICE, nay WARNING or ERROR).

In general development servers have display_errors = true and the level of error_reporting to the desired level.

Production servers has display_errors = false for whom even if an error happens this does not necessarily appear to your visitors (but stay registered in the visible log for developers).

error_reporting

display_errors