Why does using a constant to represent a class name result in a "Class not found" error?

Using a constant to represent a class name in PHP results in a "Class not found" error because constants are resolved at compile time, whereas class names are resolved at runtime. To solve this issue, you can use the actual class name directly when instantiating the class instead of using a constant. 

// Incorrect usage of constant to represent class name
define('CLASS_NAME', 'MyClass');
$obj = new CLASS_NAME(); // This will result in a "Class not found" error

// Correct way to instantiate the class using the actual class name
$obj = new MyClass();

Keywords

constant class name error PHP namespace

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