Automatic Control Principles Lesson Answers Section 12 - Automatic Loading of Classes

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Section 12--Automatic loading of classes
When you try to use an undefined class, PHP will report a fatal error. The solution is to add a class, which can be included in a file. After all, you know which class to use. However, PHP provides automatic Load function, which can save programming time. When you try to use a class that PHP has not organized into, it will look for a global function __autoload. If this function exists, PHP will call it with a parameter, which is the class's Name.
Example 6.15 illustrates how __autoload is used. It assumes that each file in the current directory corresponds to a class. When the script attempts to generate an instance of class User, PHP will execute __autoload. The script assumes that class_User.php defines There is a User class. Regardless of whether it is uppercase or lowercase when called, PHP will return the lowercase name.
Listing 6.15 Class autoloading

Copy code The code is as follows:

//define autoload function
function __autoload($class)
{
include("class_" . ucfirst($class) . ".php");
}
//use a class that must be autoloaded
$u = new User;
$u-> ;name = "Leon";
$u->printName();
?>

The above has introduced the answers to the Principles of Automatic Control course. Section 12 - Automatic loading of classes, including the answers to the Principles of Automatic Control course. I hope it will be helpful to friends who are interested in PHP tutorials.