Syntax

You can define a constant by using the define()-function or by using the const keyword outside a class definition as of PHP 5.3.0. While define() allows a constant to be defined to an arbitrary expression, the const keyword has restrictions as outlined in the next paragraph. Once a constant is defined, it can never be changed or undefined.

When using the const keyword, only scalar data (boolean, integer, float 登录查看完整内容