In what ways has PHP syntax and functionality evolved over time, and how can outdated code be updated to adhere to current best practices?

PHP syntax and functionality have evolved over time to include new features, improvements, and best practices. To update outdated PHP code to adhere to current standards, it is essential to replace deprecated functions, use modern syntax, and follow current coding conventions. This can help improve code readability, performance, and security.

// Outdated code using deprecated function
$oldArray = array(1, 2, 3);
$sum = array_sum($oldArray);

// Updated code using modern syntax
$newArray = [1, 2, 3];
$sum = array_sum($newArray);