What is the significance of the error message "Use of undefined constant" in PHP?

The error message "Use of undefined constant" in PHP indicates that a constant is being used without being defined. To fix this issue, you need to either define the constant or use the value directly without treating it as a constant. 

// Define the constant
define('MY_CONSTANT', 'Hello World');

// Correct usage of the constant
echo MY_CONSTANT;

// Incorrect usage causing the error
echo MY_CONSTANT;

Keywords

PHP error message undefined constant significance troubleshooting

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