Using settype in PHP instead of typecasting using brackets, What is the difference?

Question

In PHP you can typecast something as an object like this; (object) or you can use settype($var, "object") - but my question is what is the difference between the two?

Which one is more efficient / better to use? At the moment I find using (object) does the job, but wondering why there is a settype function as well.

Answer 1

Casting changes what the variable is being treated as in the current context, settype changes it permanently.

$value = "100"; //Value is a string
echo 5 + (int)$value; //Value is treated like an integer for this line
settype($value,'int'); //Value is now an integer

Basically settype is a shortcut for:

$value = (type)$value;

Answer 2

settype() alters the actual variable it was passed, the parenthetical casting does not.

If you use settype on $var to change it to an integer, it will permanently lose the decimal portion:

$var = 1.2;
settype($var, "integer");
echo $var; // prints 1, because $var is now an integer, not a float

If you just do a cast, the original variable is unchanged.

$var = 1.2;
$var2 = (integer) $var;
echo $var; // prints 1.2, because $var didn't change type and is still a float
echo $var2; // prints 1