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defined() function in PHP
The defined() function in PHP checks that constant exists or not.
Syntax
defined(name)
Parameters
name− The name of constant.
Return
The defined() function returns true if the constant exists otherwise false.
Example
The following is an example that checks whether a constant exist.
<?php define("myConstant","This is it!"); echo defined("myConstant"); ?>
Output
The following is the output.
1
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