Difference between phpconst and define (how to define constants in php classes)

As we all know, define defines constants. what if we define constants in a class? Of course, define cannot be used, but const can be used, for example: & amp; lt ;? Php // The constant define (& quot; PHP & quot;, & quot; phpdd is usually defined out of the class.

As we all know, define defines constants. what if we define constants in a class? Of course, define cannot be used, but const can be used, for example:

 ";}} Echo MyClass: constant ."
"; $ Classname =" MyClass "; echo $ classname: constant ."
"; // $ Class = new MyClass (); $ class-> showConstant (); echo $ class: constant ."
"; // PHP 5.3.0 and later // print_r (get_defined_constants (); // you can use get_defined_constants () to get all defined constants?>

Generally, define defines constants outside the class, const defines constants within the class, and const must be accessed by class name: variable name. However, php5.3 and above support defining constants through const outside the class, as shown below, it is OK:

     const a = "abcdef";    echo a;?>

I will not talk about the basic knowledge of constants here. apart from the above, other differences between define and const (from the network ):

1. const cannot define constants in condition statements, but define is acceptable, as follows:

2. const uses a normal constant name, and define can use an expression as the name

3. const can only accept static scalar, while define can use any expression.

4. const itself is a language structure. Define is a function. Therefore, using const is much faster.

There are so many differences between const and define in php.