PHP includes various data types such as integer, double, string and many as like as other programming languages. In this tutorial, we are going to see PHP resource data type. But, unlike other data types, it is acting as a reference or an identifier to access resource data. For example, when we attempt to access the database or a file resource, we can have a resource identifier. This identifier will be used to hook the resource to access data.
The following code shows how to get the database resource identifier by requesting the MySQL connection. In this code, the database information is specified for the mysqli_connect() and it returns MySQL connection object as a resource identifier.
$conn = mysqli_connect(localhost,"root","admin","animals");
While working with files, we need to get the file resource identifier. with the reference to this identifier, we can perform the write, append and more file manipulation operations. The following PHP code is used to create a file resource object reference.
$fp = fopen("index.php",'r');
After finishing all the operations with the resource data, the connection or the hook we created with the external resources will be cleared. The following PHP functions are used to clear the resource object reference created for the database and the file resource.