How can PHP developers effectively debug and troubleshoot issues related to variable usage?

To effectively debug and troubleshoot issues related to variable usage in PHP, developers can use var_dump() or print_r() functions to display the contents of variables and check their values during runtime. Additionally, utilizing error reporting functions like error_reporting(E_ALL) and ini_set('display_errors', 1) can help identify any errors related to variable usage. Finally, using a step-by-step debugging tool like Xdebug can provide detailed insights into variable values and their manipulation within the code.

// Example PHP code snippet demonstrating the use of var_dump() to debug variable usage
$var1 = "Hello";
$var2 = "World";
$sum = $var1 + $var2; // This will result in a warning due to incorrect variable usage

var_dump($sum); // Display the value of $sum and debug the issue