How can debugging techniques be applied in PHP to identify and resolve issues with function calls or variable assignments?

Issue: To identify and resolve issues with function calls or variable assignments in PHP, you can use debugging techniques such as printing out the values of variables, using error reporting functions like error_log(), and utilizing debugging tools like Xdebug. PHP Code Snippet:

// Example of debugging a function call
function addNumbers($num1, $num2) {
    $sum = $num1 + $num2;
    error_log("Sum of $num1 and $num2 is $sum");
    return $sum;
}

$result = addNumbers(5, 10);

// Example of debugging a variable assignment
$number = 15;
error_log("Value of number is $number");