What are some best practices for defining constants and variables in PHP to avoid errors like "Use of undefined constant" or "Undefined variable"?

When defining constants in PHP, it is important to use the `define()` function to avoid errors like "Use of undefined constant". For variables, it is best practice to always initialize them before using them to prevent "Undefined variable" errors. By following these practices, you can ensure that your code is error-free and runs smoothly. 

// Define a constant
define('PI', 3.14);

// Initialize a variable before using it
$counter = 0;

// Now you can safely use the constant and variable
echo PI * $counter;

Keywords

PHP Constants Variables Error Undefined constant

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