Echo 'string' while every long loop iteration (flush() not working)

Question

I have a loop that takes very long to execute, and I want the script to display something whenever the loop iteration is done.

echo "Hello!";

flush();

for($i = 0; $i < 10; $i ++) {
    echo $i;
    //5-10 sec execution time
    flush();
}

This does not display the echos until the entire script is completed. What went wrong?

Answer 1

From PHP Manual:

flush() may not be able to override the buffering scheme of your web server and it has no effect on any client-side buffering in the browser. It also doesn't affect PHP's userspace output buffering mechanism. This means you will have to call both ob_flush() and flush() to flush the ob output buffers if you are using those.

echo "Hello!";
flush();
ob_flush();

for($i = 0; $i < 10; $i ++) {
    echo $i;
    //5-10 sec execution time
    flush();
    ob_flush();
}

-or- you can flush and turn off Buffering

<?php
//Flush (send) the output buffer and turn off output buffering
while (ob_get_level() > 0)
    ob_end_flush();

echo "Hello!";

for($i = 0; $i < 10; $i ++) {
    echo $i . "\r\n";
}

?>

Answer 2

try this

while (@ob_end_flush());      
ob_implicit_flush(true);

echo "first line visible to the browser";
echo str_pad("",1024," ");
echo "<br />";

sleep(5);

echo "second line visible to the browser after 5 secs";

Just notice that this way you're actually disabling the output buffer for your current script. So if you're trying to 'ob_end_flush()' after that you'll get a warning that there is no buffer to close.