"Few tasks are more tedious and frustrating than debugging a Web
application. Over the years, the difficulty in doing so has grown
along with the integration of increasingly complex databases,
elaborate user authentication and privilege management solutions,
and third-party Web services. Yet many PHP developers continue to
rely upon debugging strategies that didn't work particularly well a
decade ago, let alone now. While inserting echo statements into
code in order to inspect variable data may serve to provide one
with a sense of immediate gratification, the reality is that this
approach is highly inefficient.
"Fortunately, PHP developers have a number of powerful debugging
solutions at their disposal. Whether you're merely inspecting array
contents or attempting to determine the status of an Ajax-driven
POST response, these four solutions are guaranteed to have an
immediate impact on your productivity.
"1. Configuring PHP's Error Sensitivity and Reporting"