Detailed explanation of the specific usage of ob_get_contents(), ob_end_clean(), ob_start()_PHP tutorial

ob_get_contents();
ob_end_clean();
ob_start()

Use ob_start() to output the output to the buffer , rather than to the browser.
Then use ob_get_contents to get the buffer data.
ob_start() opens a buffer on the server to save all output. So anytime echo is used, the output will be added to the buffer until the program ends or is terminated using ob_flush(). Then the content of the buffer in the server will be sent to the browser, which will be parsed and displayed by the browser.

The function ob_end_clean will clear the contents of the buffer and close the buffer, but will not output the content.
At this time, a function ob_get_contents() must be used in front of ob_end_clean() to obtain the contents of the buffer.
In this case, the content can be saved to a variable before executing ob_end_clean(), and then the variable can be operated after ob_end_clean().

This is the EG:
ob_start(); // buf1
echo ' multiple ';
ob_start(); // buf2
echo ' buffers work ';
$buf2 = ob_get_contents();
ob_end_clean();
$buf1 = ob_get_contents();
ob_end_clean();
echo $buf1;
echo '
';
echo $buf2;
ob_get_contents

(PHP 4, PHP 5)
ob_get_contents -- Return the contents of the output buffer
Description
string ob_get_contents ( void )
This will return the contents of the output buffer or FALSE, if output buffering isn't active.
See also ob_start() and ob_get_length().
if you use ob_start with a callback function as a parameter, and that function changes ob string (as in example in manual) don 't expect that ob_get_contents will return changed ob.
it will work as you would use ob_start with no parameter at all. So don't be confused.
transfer image, another method (alternative to fsockopen or function socket) :
server(192.168.0.1)
makeimage.php
.....
.....
$nameimage= "xxxx.jpg"
$comand=exec("plotvelocity.sh $nameimage $paramater1 $paramater2");
ob_start();
readfile($nameimage);
$image_data = ob_get_contents( );
ob_end_clean();
echo $image_data;
unlink($nameimage);
Client (192.168.0.2)
$bild="images/newimage2.gif";
$host="192.168.0.1";
$url=file_get_contents("http://$host/makeimage.php?$querystring");
$fp = fopen("$bild", 'wb ');
fwrite($fp, $url);
fclose($fp);
echo '';
naturally you can transfer whichever thing and not only images
ob_get_clean

(PHP 4 >= 4.3.0, PHP 5)
ob_get_clean -- Get current buffer contents and delete current output buffer
Description
string ob_get_clean ( void )
This will return the contents of the output buffer and end output buffering. If output buffering isn't active then FALSE is returned. ob_get_clean() essentially executes both ob_get_contents() and ob_end_clean().

Example 1. A simple ob_get_clean() example

Copy code The code is as follows:

ob_start();
echo "Hello World";
$out = ob_get_clean();
$out = strtolower($out);
var_dump($out) ;
?>

Our example will output: string(11) "hello world"
See also ob_start() and ob_get_contents().
Notice that the function beneath does not catch errors, so throw in an @ before those ob_* calls
Running PHP4 < 4.3.0, you can simply add the following to use the function anyway:

Copy the code The code is as follows:

if (!function_exists("ob_get_clean")) {
function ob_get_clean() {
$ ob_contents = ob_get_contents();
ob_end_clean();
return $ob_contents;
}
}
?>

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