What are the potential issues or errors that may arise when using ob_start() and ob_get_contents() in PHP for measuring data sent to the client?

One potential issue that may arise when using ob_start() and ob_get_contents() in PHP for measuring data sent to the client is that the output buffer may not be properly cleared after retrieving its contents, leading to inaccurate measurements. To solve this issue, it is important to clear the output buffer using ob_end_clean() or ob_end_flush() after retrieving the contents.

ob_start();

// Output some content here

$output = ob_get_contents();

ob_end_clean();

// Use $output for measurements or further processing