Zend supports the creation of true constants (as opposed to regular variables). Constants are accessed without the typical dollar sign ($) prefix and are available in all scopes. Examples include TRUE and FALSE, to name just two.
To create your own constants, you can use the macros in 表33-6. All the macros create a constant with the specified name and value.
You can also specify flags for each constant:
CONST_CS - This constant's name is to be treated as case sensitive.
CONST_PERSISTENT - This constant is persistent and won't be "forgotten" when the current process carrying this constant shuts down.
表 33-6Macros for Creating Constants