Loop PHP check until text within webpage has been found - php

Question

On pressing the submit button, I want the PHP code to check to see if a string exists within a webpage on another website.
$random = rand(100,1000);
strpos(file_get_contents('website.com/url.php?username='.$username), $random);
So, until the code has managed to find the value of $random, it won't continue with the rest of the script. The updates can take about 10 seconds.
I have tried a while script:
$random = rand(100,1000);
echo '<div data-alert class="alert-box alert">'.$random.'</div>';
$key = false;
while($key){
if(strpos(file_get_contents('website.com/url.php?username='.$username), $random)) $key = true;
}
This doesn't seem to work.

Answer 1

On pressing the submit button, I want the PHP code to check to see if a string exists within a webpage on another website.
If I understood your question correctly, try this:
$content = file_get_contents($url);
if(str_replace($string, "", $content) != $content)
echo "found";
EDIT:
do {
$content = file_get_contents($url);
} while(strpos($content, $string) === false);
EDIT 2:
$i = 0;
do {
$content = file_get_contents($url);
$i++;
} while(strpos($content, $string) === false && $i <= 100);
EDIT 3:
$i = 0;
do {
$content = file_get_contents($url);
$i++;
} while(strpos($content, $string) === false && $i <= 100);
if($i > 100){
echo "nothing found";
}
EDIT 4:
$startTime = time();
do {
$content = file_get_contents($url);
} while(strpos($content, $string) === false && time() - $startTime < 30);
if(time() - $startTime > 30){
echo "nothing found";
}