How to let the negative operator after using diff() in php

Question

Good afternoon. I do not know if it was very clear but the following, use date_diff(), the problem is what, when I convert the interval $intervalo = date_interval_format($resultado, '%a') if the result is less than 0 the number is positive, and is disturbing my logic, because I need that when the deadline is in delay, I can identify, only that when I make a difference and is late 30 days (-30), my code is interpreting that is missing 30 days, for it is positive. how can I solve, code below:

$database = date_create($row['expira']);
$datadehoje = date_create();
$resultado = date_diff($database, $datadehoje);
$intervalo = date_interval_format($resultado, '%a');
echo $intervalo;

Answer 1

The result of the comparison is always the number of days but there is an attribute in the object returned by date_diff() called invert indicating whether the value is positive or negative (zero for positive numbers and one for negative).

<?php

    $primeiraData = date_create('2018-12-01');
    $segundaData = date_create('2018-12-31');

    $intervalos[0] = date_diff($primeiraData, $segundaData);
    $intervalos[1] = date_diff($segundaData, $primeiraData);

    foreach ($intervalos as $intervalo){
        $diferenca = (int)$intervalo->format('%R%a');
        echo "'Diferença de " . $diferenca . " dias (" . $intervalo->invert . ")'\n";
    }
?>

Running the program will display this:

'Diferença de 30 dias (0)'
'Diferença de -30 dias (1)'

If you only want to display the amount of days on the screen you can use the "%R" on string value formatting but if you want to work with this value in some calculation you will need to use the invert to change the signal.