How to use the define () function in PHP

This article mainly introduces how to use the define () function in PHP, which has a certain reference value, and interested friends can refer to it. I hope you will gain a lot after reading this article.

PHP constant

Constants are similar to variables, but once a constant is defined, it cannot be changed or undefined.

A constant is the identifier (name) of a single value. The value cannot be changed in the script.

Valid constant names begin with a character or underscore (the constant name is not preceded by a $sign).

Tip: unlike variables, constants are automatically global throughout the script.

Set PHP constant

To set a constant, use the define () function, which takes three parameters:

The first parameter defines the name of the constant

The second parameter defines the value of the constant

The optional third parameter specifies whether the constant name is case-sensitive. The default is false.

The following example creates a case-sensitive constant with a value of "Welcome to HuluMiao.cn!":

The following example creates a case-insensitive constant with a value of "Welcome to HuluMiao.cn!":

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