What best practices should PHP developers follow to prevent undefined constant errors in their code?

To prevent undefined constant errors in PHP code, developers should always use quotes around string constants to avoid PHP interpreting them as undefined constants. This ensures that PHP treats them as string literals and does not throw undefined constant errors. 

// Incorrect way without quotes
define(HELLO, "Hello, World!");

// Correct way with quotes
define('HELLO', "Hello, World!");

Keywords

PHP constant error define strict mode

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