Uneven division of an integer variable by another integer variable will result in a float by automatic conversion -- you do not have to cast the variables to floats in order to avoid integer truncation (as you would in C, for example):

$dividend = 2;
$divisor = 3;
$quotient = $dividend/$divisor;
print $quotient; / 0.66666666666667

Cast operators have a very high precedence, for example (int)$a/$b is evaluated as ((int)$a)/$b, not as (int)($a/$b) [which would be like intdiv($a,$b) if both $a and $b are integers].
The only exceptions (as of PHP 8.0) are the exponentiation operator ** [i.e. (int)$a**$b is evaluated as (int)($a**$b) rather than ((int)$a)**$b] and the special access/invocation operators ->, ::, [] and () [i.e. in each of (int)$a->$b, (int)$a::$b, (int)$a[$b] and (int)$a($b), the cast is performed last on the result of the variable expression].

Type casting in expressions is executed first.
The casting is assigned to the value, not to the expression result.
Examples:

<?php

$string = "777";

var_dump( $string === 777 );            / FALSE
var_dump( (int)  $string === 777 );     / TRUE
var_dump( ( (int) $string ) === 777 );  / TRUE
var_dump( (int) ( $string === 777 ) );  / 0
?>

Casting objects to arrays is a pain. Example:

<?php

class MyClass {

    private $priv = 'priv_value';
    protected $prot = 'prot_value';
    public $pub = 'pub_value';
    public $MyClasspriv = 'second_pub_value';

}

$test = new MyClass();
echo '<pre>';
print_r((array) $test);

/*
Array
(
    [MyClasspriv] => priv_value
    [*prot] => prot_value
    [pub] => pub_value
    [MyClasspriv] => second_pub_value
)
 */

?>

Yes, that looks like an array with two keys with the same name and it looks like the protected field was prepended with an asterisk. But that's not true:

<?php

foreach ((array) $test as $key => $value) {
    $len = strlen($key);
    echo "{$key} ({$len}) => {$value}<br />";
    for ($i = 0; $i < $len; ++$i) {
        echo ord($key[$i]) . ' ';
    }
    echo '<hr />';
}

/*
MyClasspriv (13) => priv_value
0 77 121 67 108 97 115 115 0 112 114 105 118
*prot (7) => prot_value
0 42 0 112 114 111 116
pub (3) => pub_value
112 117 98
MyClasspriv (11) => second_pub_value
77 121 67 108 97 115 115 112 114 105 118
 */

?>

The char codes show that the protected keys are prepended with '\0*\0' and private keys are prepended with '\0'.__CLASS__.'\0' so be careful when playing around with this.

If you want to convert a string automatically to float or integer (e.g. "0.234" to float and "123" to int), simply add 0 to the string - PHP will do the rest.

e.g.

$val = 0 + "1.234";
(type of $val is float now)

$val = 0 + "123";
(type of $val is integer now)

Printing or echoing a FALSE boolean value or a NULL value results in an empty string:
(string)TRUE /returns "1"
(string)FALSE /returns ""
echo TRUE; /prints "1"
echo FALSE; /prints nothing!