How to use php defined function

php defined function is used to check whether a certain constant exists. Its syntax is defined(name). The parameter name is required and refers to the name of the constant to be checked.

#How to use php defined function?

Definition and usage

defined() function checks whether a constant exists.

Syntax

defined(name)

Parameters

name Required. Specifies the name of the constant to be checked.

Return value: TRUE if the constant exists, otherwise FALSE.

PHP Version: 4

Example

Check whether a constant exists:

Output:

1

The above is the detailed content of How to use php defined function. For more information, please follow other related articles on the PHP Chinese website!