使用javascript从textarea获取原始文本并将其发送到PHP

I have a textarea where I put some C++ code, then I get that code with javascript and send it to a PHP script via AJAX to be processed. The problem is that the code gets corrupted in the way.

Here is my code:

function showResult()
{
  var code  = document.getElementById('code').value;
  var input = document.getElementById('input').value;

  if (code != '') {
    var xmlhttp;
    if (window.XMLHttpRequest) {
      xmlhttp = new XMLHttpRequest();
    }

    xmlhttp.onreadystatechange = function() {
      if (xmlhttp.readyState == 4 && xmlhttp.status == 200) {
        document.getElementById('result').innerHTML = xmlhttp.responseText;
      }
    }

    xmlhttp.open('GET', 'ideone.php?code=' + code + '&input=' + input, true);
    xmlhttp.send();
  }

}

PHP:

<?php
    echo 'Code: '.$_GET['code']; // Empty string
?>

You need to quote your query string:

xmlhttp.open('GET', 'ideone.php?code=' + encodeURIComponent(code) + '&input=' + encodeURIComponent(input), true);