Type Hinting

• Primitive types: int, float, bool, string.
• Classes and interfaces: Any class or interface name.
• Arrays: with the array keyword.
• Callable: for functions or objects that implement the invoke method.
• Nullable types: by prefixing with a ?.
• Iterables: with the iterable keyword, which includes both arrays and objects implementing the
  Traversable interface.
• Union types: introduced in PHP 8, where a parameter can accept multiple types.

// Type Hinting - int, float, bool, string

function myage(int $age){
echo $age."\n";
}
myage(5);