Why is it recommended to have functions in PHP return values instead of directly outputting them with echo?

It is recommended to have functions in PHP return values instead of directly outputting them with echo because it allows for better code organization, reusability, and flexibility. By returning values, you can store the result in a variable and use it in multiple places within your code. This also makes the function more testable and easier to debug.

// Incorrect way - directly outputting with echo
function add($a, $b) {
    echo $a + $b;
}

add(2, 3); // Output: 5

// Correct way - returning the value
function add($a, $b) {
    return $a + $b;
}

$result = add(2, 3);
echo $result; // Output: 5