Question

In my PHP code I have a variable that corresponds to the sum and difference of some values obtained ​​from a MySQL database. This is the code:

<?php echo $verifica = (($valoreEntrate + $valoreInCassa) - ($valoreUscite + $valorePagamentiInSospeso + $valoreDaLasciareInCassa + $valoreDaPortareACasa)); ?>

Here is values of all variables involved obtained with echo:

$valoreEntrate = 3837.67
$valoreInCassa = 612.10
$valoreUscite = 97.81
$valorePagamentiInSospeso = 0
$valoreDaLasciareInCassa = 617.80
$valoreDaPortareACasa = 3734.22

The value of $verifica is:

$verifica = -0.0599999999995

Instead of -0.6 like I expected…
Can anyone explain why this value?
Thank you so much!!!
Bye…

Answer 1

This is because they are float types, and floats are not stored as exact numbers. See PHP’s entry on float for further information.