In PHP, you can use the gettype() function to determine the data type of a value. This function returns a string that represents the data type of the value passed to it. For example:

$num = 10;
$str = "hello";
$bool = true;
$arr = array(1, 2, 3);

echo gettype($num); // integer
echo gettype($str); // string
echo gettype($bool); // boolean
echo gettype($arr); // array

In this example, the gettype() function will return integer for the $num variable, string for the $str variable, boolean for the $bool variable, and array for the $arr variable.

You can also use the is_* functions to check the data type of a value. For example, you can use is_int() to check if a value is an integer, is_string() to check if a value is a string, and so on. For example:

$num = 10;
$str = "hello";
$bool = true;
$arr = array(1, 2, 3);

if (is_int($num)) {
echo "num is an integer";
}
if (is_string($str)) {
echo "str is a string";
}
if (is_bool($bool)) {
echo "bool is a boolean";
}
if (is_array($arr)) {
echo "arr is an array";
}

This will output “num is an integer”, “str is a string”, “bool is a boolean”, and “arr is an array”.

You can also use the instanceof operator to check if an object is an instance of a particular class. For example:

class MyClass {
}

$obj = new MyClass();

if ($obj instanceof MyClass) {
echo "obj is an instance of MyClass";
}

This will output “obj is an instance of MyClass”.