Output Text in PHP While Loop (while page is still working?)

Question

I have a simple php page, that is doing some operations for an mysql result set:

$i = $d = $n = 0;

$sql="SELECT record, field1,field2,field3 from table where condition='xxxx'" ;
result=$db->send_sql($sql);

while($row=mysql_fetch_array($result, MYSQL_ASSOC))
{
  //about 500 results
  //now performing some actions on these results via function call
  $i++;
  if($row['field1'] == 'xxx')
  {
    $d++;
    echo $row['record'].": ";
    echo do_something(field1,field2); //function will echo some text
    echo "<br>";
  }
  else
  {
    $n++;
    echo $row['record'].": nothing to do <br>";
  }
}
echo "<hr>Total: ".$i." - Updates: ".$d." - Nothing done: ".$n;

All works, as it should but the Output/echos are only shown, once all operations have been done and the while statement has been worked through.

It might be a silly question, but is there a way to show the "echos/output" "on the fly" - so the user get's the "something is happening" experience?

If you're wanting it to dynamically update, then you should look at AJAX and long-polling. — Ben Fortune, Nov 19 '13 at 14:26
Thanks Ram for correcting my typos (shame on me ...) Here's what worked for me, based on the answers below: echo str_repeat(" ", 256)."
\r\n"; flush(); — Christian K., Nov 19 '13 at 14:48

score 1 · Answer 1 · answered Nov 19 '13 at 14:28

1

PHP is run on the server and displays output to the client when it is finished. I think you will need Javascript to do this, but I could be wrong.

answered Nov 19 '13 at 14:28

CoryClough

11
1

score 1 · Accepted Answer · edited May 23 '17 at 12:28

echo sends the output toward the user immediately, but that output might be held up by a couple of layers in between. If you want the feel you describe, use AJAX. Otherwise, you can try some of these approaches:

Turn output buffering off
flush() immediately after sending your HTML head element
then flush() periodically, with some str_repeat() to kickstart/prevent timeouts

See also this and this conversation on performance/best practices and this conversation on output buffering.

score 0 · Answer 3 · answered Nov 19 '13 at 14:28

0

You can try to use flush() function to send data to browser after each loop execution.

answered Nov 19 '13 at 14:28

Elon Than

9,603
4
27
37

Flush is the way to do it here, if you by any chance is using output buffering then adding an ob_flush() would be advised. – Jesper Blaase Nov 19 '13 at 14:32
unfortunately the output will be visible once the whole script is finished so this is not solution – Mirosław Karczmarczyk Nov 19 '13 at 14:34

Output Text in PHP While Loop (while page is still working?)

3 Answers3