(PECL apc >= 3.0.0)
apc_define_constants — Defines a set of constants for retrieval and mass-definition
define() is notoriously slow. Since the main benefit of APC is to increase the performance of scripts/applications, this mechanism is provided to streamline the process of mass constant definition. However, this function does not perform as well as anticipated.
For a better-performing solution, try the » hidef extension from PECL.
Note: To remove a set of stored constants (without clearing the entire cache), an empty array may be passed as the constants parameter, effectively clearing the stored value(s).
The key serves as the name of the constant set being stored. This key is used to retrieve the stored constants in apc_load_constants().
An associative array of constant_name => value pairs. The constant_name must follow the normal constant naming rules. value must evaluate to a scalar value.
The default behaviour for constants is to be declared case-sensitive; i.e. CONSTANT and Constant represent different values. If this parameter evaluates to FALSE the constants will be declared as case-insensitive symbols.
如果成功则返回 TRUE，失败则返回 FALSE。
Example #1 apc_define_constants() example
<?php
$constants = array(
'ONE' => 1,
'TWO' => 2,
'THREE' => 3,
);
apc_define_constants('numbers', $constants);
echo ONE, TWO, THREE;
?>
上例将输出：
123