Core PHP Programming, Third Edition

7.3. Output Buffering

As stated, the Web server buffers content sent to the browser, and you can request that the buffer be flushed. PHP also includes a mechanism for buffering output you can control completely. Among the output buffering functions described in Chapter 8 are ob_start, ob_end_flush, and ob_end_clean.

When you call the ob_start function, PHP places anything you send to the browser into a buffer. This includes text outside of PHP tags. The Web server does not receive this content until you call the ob_end_flush function. There are several powerful applications of these functions. One is to avoid the problem associated with sending headers. Because PHP sends all headers at once, before any content, you have to take care when using ...