Are there any reliable online resources or tables for understanding and managing resource states in PHP?

Understanding and managing resource states in PHP can be challenging, as resources are special variables that hold references to external resources like database connections or file handles. To properly handle these resources, it's important to check their state before using them and properly release them when no longer needed to avoid memory leaks. One reliable online resource for understanding resource states in PHP is the official PHP documentation on resources.

// Check if a resource is valid before using it
if (is_resource($resource)) {
    // Use the resource here
} else {
    // Handle the case where the resource is not valid
}

// Release the resource when no longer needed
fclose($resource);