How can the error_reporting function be effectively used to debug PHP code and display error messages in the browser?

To effectively debug PHP code and display error messages in the browser, you can use the error_reporting function to set the level of errors to display. By setting the error_reporting level to E_ALL, all errors, warnings, and notices will be displayed. This can help identify and fix issues in the code more efficiently.

```php
error_reporting(E_ALL);
ini_set('display_errors', 1);
```

By adding these two lines of code at the beginning of your PHP script, you can ensure that all errors are displayed in the browser, making it easier to identify and resolve issues in your code.