getting json is null output when run on PHP5.1.6

Question

I am trying to get a 2 dimensional array from php using ajax and jquery.

The problem is that when I run it in php5.4.7 I am getting the expected json response

[["A",46],["B",35],["C",68],["D",30],["E",27],["F",85]]

But with php5.1.6 i am getting a response that json is null . How can I make it work in PHP5.1.6??

$.ajax({
    type: "POST",
    url: "get_data.php",
    data: "",
    dataType: "json",
    success: function (json) {
        var data = json;

        initChart(data);
    }
});

---

header('Content-Type: application/json');

$arr=array();
$arr = array(
    array('A', 46),
    array('B', 35),
    array('C', 68),
    array('D', 30),
    array('E', 27),
    array('F', 85),
);
echo json_encode($arr);

Answer 1

json_encode requires version > 5.2.0

For backward compatibility use below code

if (!function_exists('json_encode'))
{
function json_encode($a=false)
{
if (is_null($a)) return 'null';
if ($a === false) return 'false';
if ($a === true) return 'true';
if (is_scalar($a))
{
  if (is_float($a))
  {
    // Always use "." for floats.
    return floatval(str_replace(",", ".", strval($a)));
  }

  if (is_string($a))
  {
    static $jsonReplaces = array(array("\\", "/", "\n", "\t", "\r", "\b", "\f", '"'), array('\\\\', '\\/', '\\n', '\\t', '\\r', '\\b', '\\f', '\"'));
    return '"' . str_replace($jsonReplaces[0], $jsonReplaces[1], $a) . '"';
  }
  else
    return $a;
}
$isList = true;
for ($i = 0, reset($a); $i < count($a); $i++, next($a))
{
  if (key($a) !== $i)
  {
    $isList = false;
    break;
  }
}
$result = array();
if ($isList)
{
  foreach ($a as $v) $result[] = json_encode($v);
  return '[' . join(',', $result) . ']';
}
else
{
  foreach ($a as $k => $v) $result[] = json_encode($k).':'.json_encode($v);
  return '{' . join(',', $result) . '}';
}
}
}