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?

Answer 1

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

Answer 2

It's worth mentioning that settype does NOT change the variable type permanently. The next time you set the value of the variable, PHP will change its type as well.

$value = "100"; //Value is a string
echo 5 + (int)$value; //Value is treated like an integer for this line
settype($value,'int'); //Value is now an integer
$value = "Hello World"; //Now value is a string
$value = 7; // Now value is an integer

Type Juggling can be frustrating but if you understand what's happening and know your options it can be managed. Use var_dump to get the variables type and other useful info.

Answer 3

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;