Everyone should know that define and const are constants in PHP, but how much do you know about them? This article mainly shares with you a detailed explanation of the difference between define and const in PHP, hoping to help everyone.
There is no dollar sign ($) in front of the constants;
Constants can only be used define() function definition, not through assignment statements;
Constants can be defined and accessed anywhere regardless of the scope of the variable;
Once defined, a constant cannot be redefined or undefined;
The value of a constant can only be a scalar.
| Use of const | Use of define |
|---|---|
| const is used for the definition of class constants | Define cannot be used for the definition of class constants, but can be used for global constants. |
| You cannot use const to define constants within functions, loops, and if statements. | define can use an ordinary constant name |
| const | define can use an expression as the name |
| const can only accept static scalars | define can use any expression |
| const-defined constants are case-sensitive | define can use the first Three parameters (true indicates case insensitivity) to specify whether case sensitivity is present. |
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Detailed examples of the difference between the usage of php constants define and const
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