What are the best practices for defining variables in PHP to avoid undefined index or undefined variable notices?

To avoid undefined index or undefined variable notices in PHP, it is best practice to check if a variable or array key exists before using it. This can be done using isset() or empty() functions to ensure that the variable or array key is defined before accessing its value. 

// Example of defining variables in PHP to avoid undefined index or undefined variable notices

// Check if the variable is set before using it
$variable = isset($_POST['variable']) ? $_POST['variable'] : '';

// Check if the array key exists before accessing its value
$array = [];
$value = isset($array['key']) ? $array['key'] : '';

Keywords

PHP variables undefined index undefined variable error notices

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