PHP: Output Control Functions - Manual

flush — Flush system output buffer
ob_clean — Clean (erase) the contents of the active output buffer
ob_end_clean — Clean (erase) the contents of the active output buffer and turn it off
ob_end_flush — Flush (send) the return value of the active output handler and turn the active output buffer off
ob_flush — Flush (send) the return value of the active output handler
ob_get_clean — Get the contents of the active output buffer and turn it off
ob_get_contents — Return the contents of the output buffer
ob_get_flush — Flush (send) the return value of the active output handler, return the contents of the active output buffer and turn it off
ob_get_length — Return the length of the output buffer
ob_get_level — Return the nesting level of the output buffering mechanism
ob_get_status — Get status of output buffers
ob_implicit_flush — Turn implicit flush on/off
ob_list_handlers — List all output handlers in use
ob_start — Turn on output buffering
output_add_rewrite_var — Add URL rewriter values
output_reset_rewrite_vars — Reset URL rewriter values

Found A Problem?

18 years ago

It seems that while using output buffering, an included file which calls die() before the output buffer is closed is flushed rather than cleaned. That is, ob_end_flush() is called by default.

<?php
// a.php (this file should never display anything)
ob_start();
include('b.php');
ob_end_clean();
?>

<?php
// b.php
print "b";
die();
?>

This ends up printing "b" rather than nothing as ob_end_flush() is called instead of ob_end_clean(). That is, die() flushes the buffer rather than cleans it. This took me a while to determine what was causing the flush, so I thought I'd share.

Anonymous ¶

17 years ago

You possibly also want to end your benchmark after the output is flushed.

<?php
your_benchmark_start_function();

ob_start ();
for ($i = 0; $i < 5000; $i++)
    echo str_repeat ("your string blablabla bla bla", (rand() % 4) + 1)."<br>\n";

                              <----------
echo your_benchmark_end_function();      |
ob_end_flush (); ------------------------
?>

gruik at libertysurf dot fr ¶

21 years ago

For those who are looking for optimization, try using buffered output.

I noticed that an output function call (i.e echo()) is somehow time expensive. When using buffered output, only one output function call is made and it seems to be much faster.
Try this :

<?php
your_benchmark_start_function();

for ($i = 0; $i < 5000; $i++)
    echo str_repeat ("your string blablabla bla bla", (rand() % 4) + 1)."<br>\n";

echo your_benchmark_end_function();
?>

And then :

<?php
your_benchmark_start_function();

ob_start ();
for ($i = 0; $i < 5000; $i++)
    echo str_repeat ("your string blablabla bla bla", (rand() % 4) + 1)."<br>\n";

echo your_benchmark_end_function();
ob_end_flush ();
?>

PHP: Output Control Functions - Manual

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Found A Problem?