PHP: How to progressively output inside a loop?

Question

I have a loop and each iteration takes N seconds.

for($i=0;$i<10;$i++) {
 echo $i;
 process(); // 10 seconds process
}

Is there a way to output progressively (in web page) $i without having to wait until the whole loop ends ?

look into php.net/manual/en/function.ob-flush.php

Jeff
– Jeff

2019-04-16 11:29:06 +00:00
Commented Apr 16, 2019 at 11:29 — Jeff
– Jeff, Commented Apr 16, 2019 at 11:29

Shanteshwar Inde · Accepted Answer · 2019-07-11 09:23:20Z

5

Flushes the system write buffers of PHP and whatever backend PHP is using (CGI, a web server, etc). This attempts to push current output all the way to the browser with a few caveats.

<?php
  if (ob_get_level() == 0) ob_start();
  for ($i = 0; $i<10; $i++) {
    echo "<br> Line to show.";
    echo str_pad('',4096)."\n";    
    ob_flush();
    flush();
    sleep(2);
  }
  echo "Done.";
  ob_end_flush();
?>

Read documentation here.

EDIT:

str_pad() - Pad a string to a certain length with another string. and Some versions of Microsoft Internet Explorer will only start to display the page after they have received 256 bytes of output, so you may need to send extra whitespace before flushing to get those browsers to display the page. that's why use str_pad() for be safe side.

edited Jul 11, 2019 at 9:23

answered Apr 16, 2019 at 11:29

Shanteshwar Inde

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2 Comments

yarek Over a year ago

That is this str_pad for and Who Paddington smith 4096 chars ?

Shanteshwar Inde Over a year ago

@yarek added explanation for that, hopefully this will help you to understand.

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