void flush ( void )

Flushes the system write buffers of PHP

This attempts to push current output all the way to the browser with a few caveats.

* Server modules for Apache like mod_gzip may do buffering of their own that will cause flush() to not result in data being sent immediately to the client.

* Even the browser may buffer its input before displaying it.

void ob_flush ( void )

This function will send the contents of the output buffer (if any).

i.e.

ob_flush();
flush();