(PHP 4, PHP 5, PHP 7)
class_exists — 锟斤拷锟斤拷锟斤拷欠锟斤拷讯锟斤拷锟�
$class_name
[, bool $autoload = true
] ) : bool锟斤拷锟街革拷锟斤拷锟斤拷锟斤拷欠锟斤拷讯锟斤拷濉�
锟斤拷锟斤拷锟� class_name
锟斤拷指锟斤拷锟斤拷锟窖撅拷锟斤拷锟藉，锟剿猴拷锟斤拷锟斤拷锟斤拷
TRUE锟斤拷锟斤拷锟津返伙拷 FALSE锟斤拷
Example #1 class_exists() 锟斤拷锟斤拷
<?php
// 使锟斤拷前锟斤拷锟斤拷锟斤拷欠锟斤拷锟斤拷
if (class_exists('MyClass')) {
$myclass = new MyClass();
}
?>
Example #2 autoload parameter 锟斤拷锟斤拷
<?php
function __autoload($class)
{
include($class . '.php');
// Check to see whether the include declared the class
if (!class_exists($class, false)) {
trigger_error("Unable to load class: $class", E_USER_WARNING);
}
}
if (class_exists('MyClass')) {
$myclass = new MyClass();
}
?>