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With PHP3, all of the content produced
by echo () or print() was sent directly to the server. In PHP4, an
intermediate storage layer makes it possible to defer the sending the Web
server’s output flow. To do this, features so new they have yet to be documented, are available:
-
ob_start(): activates
output buffering -
ob_end_flush(): sends the
contents of the output buffer and deactivates buffering -
ob_end_clean(): empties the
output buffer and deactivates buffering -
ob_get_contents(): returns
the output buffer contents
This functionality makes it possible to prepare the
contents displayed via complex processes requiring several
database queries, for example, and the sending of results only when all of
the queries have been carried out successfully. In the opposite case, users
can empty the output buffer contents and display an error message in its
place. The example below shows a typical case of how these functionalities
are used:
|
<?php
// activate output buffers ob_start(); // the output is not displayed, it enters the buffer print “Hello, world!”; // read buffer contents $output = ob_get_contents(); // deactivate the buffer, empty the buffer ob_end_clean(); // display contents $output; ?> |
