How can the functions in the PHP code be improved to provide more reusability and efficiency in future projects?

To improve reusability and efficiency in future projects, the functions in the PHP code can be refactored to follow the principles of DRY (Don't Repeat Yourself) and separation of concerns. This can be achieved by breaking down the functions into smaller, more specialized functions that perform specific tasks, making them easier to reuse in different parts of the codebase. Additionally, using parameters to pass data into functions instead of relying on global variables can make the code more flexible and easier to maintain.

// Example of refactored functions for improved reusability and efficiency

// Function to calculate the sum of two numbers
function calculateSum($num1, $num2) {
    return $num1 + $num2;
}

// Function to calculate the product of two numbers
function calculateProduct($num1, $num2) {
    return $num1 * $num2;
}

// Example usage
$sum = calculateSum(5, 3);
$product = calculateProduct(5, 3);

echo "Sum: $sum, Product: $product";