How can the use of echo versus return in PHP functions impact the overall functionality of a script, as shown in the forum thread?

Using echo versus return in PHP functions can impact the overall functionality of a script because echo is used to output data to the screen, while return is used to pass data back to the calling code. If a function uses echo instead of return, the output will be displayed directly on the screen instead of being stored in a variable or used in further calculations. To fix this issue, make sure to use return when you want to pass data back to the calling code.

// Incorrect usage of echo in a function
function calculateSum($num1, $num2) {
    echo $num1 + $num2;
}

// Corrected function using return
function calculateSum($num1, $num2) {
    return $num1 + $num2;
}

// Calling the corrected function and storing the result in a variable
$sum = calculateSum(5, 3);
echo $sum; // Output: 8