How can one prevent or handle the error message "Use of undefined constant" in PHP scripts?

To prevent or handle the error message "Use of undefined constant" in PHP scripts, make sure to enclose the constant in quotes when using it as a string value or define the constant before using it in the script. 

// Define the constant before using it
define('MY_CONSTANT', 'my_value');

// Proper usage of the constant with quotes
echo MY_CONSTANT;

Keywords

PHP constant error handling defined undefined

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