PHP defined () function

Definition and usage
Definition and usage

The defined () function checks whether a constant exists.
The role of the defined () function is to checkConstantWhether it exists.

Returns true if the constant exists, or false otherwise.
If the constant exists, true is returned. If the constant does not exist, false is returned.

Syntax
Syntax

defined(name)

Parameter Parameters	Description Description
Name	Required. specifies the name of the constant to check Required parameter. Constant Object Name

Example
Case <? PHP
Define ("greeting", "hello you! How are you today? ");
Echo defined ("greeting ");
?>

 

 

The output of the code above will be:
The above code will output the following results:

1