zero¶

Zero is the 0 integer. Zero is part of the falsy values: it is the equivalent of false.

It is often used to return successful execution, where non-zero answers are unsuccessful execution, represented by their error message.

Adding 0 to a string turns it into an integer, just like the cast operator (int) does.

Comparisons between 0 and other falsy values, such as empty string '' changed with PHP 8.0: it was true and became false.

Division by zero emits the DivisionByZeroError, as that operation is impossible. Multiplication is possible and always returns 0.

0 is one of the two valid index when building a callback with an array, along with 1.

0 is a classic magic number, although it has so many uses that it is usually look over, as generating too many false positives or scattered issues.

<?php

    $zero = 0;

    $four = 4 + 0;

?>