Question

Say we have page 1:

<?php
$text=$_POST['text'];
echo 'You wrote "' . $text . '".';
?>

and page 2, which takes the user input, POSTs it to Page1, and gets the page (You wrote (input).). I’m not really sure about how to do this: googling (or better, stackoverflowing) a while, I found this question, which explains how to POST a variable to another page, but not how to get the code of the page. So, how to do both?

EDIT: An example of the actual situation.
The user inputs the number 245. I get the number, pass it to this external page, get the page, retrieve the result (5*7*7) and show it.
In italics you see the part I need.

Answer 1

Working example with cURL:

$function="sin(x)";
$var="x";
$url='http://www.numberempire.com/integralcalculator.php';
echo '<base href="' . $url . '">'; // Fixes broken relative links
$Curl_Session = curl_init($url);
curl_setopt ($Curl_Session, CURLOPT_POST, 1);
curl_setopt ($Curl_Session, CURLOPT_POSTFIELDS, "function=$function&var=$var");
curl_setopt ($Curl_Session, CURLOPT_FOLLOWLOCATION, 0);
$content=curl_exec($Curl_Session);
curl_close ($Curl_Session);