ob_startTurn on output buffering
&reftitle.description;
boolob_startcallbackoutput_callbackintchunk_sizeboolerase
This function will turn output buffering on. While output buffering is
active no output is sent from the script (other than headers), instead the
output is stored in an internal buffer.
The contents of this internal buffer may be copied into a string variable
using ob_get_contents. To output what is stored in
the internal buffer, use ob_end_flush. Alternatively,
ob_end_clean will silently discard the buffer
contents.
Some web servers (e.g. Apache) change the working directory of a script
when calling the callback function. You can change it back by e.g.
chdir(dirname($_SERVER['SCRIPT_FILENAME'])) in the
callback function.
Output buffers are stackable, that is, you may call
ob_start while another
ob_start is active. Just make
sure that you call ob_end_flush
the appropriate number of times. If multiple output callback
functions are active, output is being filtered sequentially
through each of them in nesting order.
&reftitle.parameters;
output_callback
An optional output_callback function may be
specified. This function takes a string as a parameter and should
return a string. The function will be called when
the output buffer is flushed (sent) or cleaned (with
ob_flush, ob_clean or similar
function) or when the output buffer
is flushed to the browser at the end of the request. When
output_callback is called, it will receive the
contents of the output buffer as its parameter and is expected to
return a new output buffer as a result, which will be sent to the
browser. If the output_callback is not a
callable function, this function will return &false;.
If the callback function has two parameters, the second parameter is
filled with a bit-field consisting of
PHP_OUTPUT_HANDLER_START,
PHP_OUTPUT_HANDLER_CONT and
PHP_OUTPUT_HANDLER_END.
If output_callback returns &false; original
input is sent to the browser.
The output_callback parameter may be bypassed
by passing a &null; value.
ob_end_clean, ob_end_flush,
ob_clean, ob_flush and
ob_start may not be called from a callback
function. If you call them from callback function, the behavior is
undefined. If you would like to delete the contents of a buffer,
return "" (a null string) from callback function.
You can't even call functions using the output buffering functions like
print_r($expression, true) or
highlight_file($filename, true) from a callback
function.
In PHP 4.0.4, ob_gzhandler was introduced to
facilitate sending gz-encoded data to web browsers that support
compressed web pages. ob_gzhandler determines
what type of content encoding the browser will accept and will return
its output accordingly.
chunk_size
If the optional parameter chunk_size is passed, the
buffer will be flushed after any output call which causes the buffer's
length to equal or exceed chunk_size.
Default value 0 means that the function is called only in the end,
other special value 1 sets chunk_size to 4096.
erase
If the optional parameter erase is set to &false;,
the buffer will not be deleted until the script finishes.
This causes that flushing and cleaning functions would issue a notice
and return &false; if called.
&reftitle.returnvalues;
&return.success;
&reftitle.changelog;
&Version;&Description;6.0.0
Value 1 is no more special.
4.3.2
This function was changed to return &false; in case the passed
output_callback can not be executed.
4.2.0
Added the erase parameter.
&reftitle.examples;
User defined callback function example