getting error while converting xml to json-Collection of common programming errors

I am getting undefined function error when i am using json_encode() function. I need to convert the xml data to json data. The code i am using is :

$xml = simplexml_load_string($retValue);
echo json_encode($xml);

I also tried this:

$xml = simplexml_load_string($retValue);
$array = objectsIntoArray($xml);
$array = json_encode($array);
print_r($array);
die;

function objectsIntoArray($arrObjData, $arrSkipIndices = array())
{

    $arrData = array();
    if (is_object($arrObjData)) {
        $arrObjData = get_object_vars($arrObjData);
    }
    if (is_array($arrObjData)) {
        foreach ($arrObjData as $index => $value) {
            if (is_object($value) || is_array($value)) {
                $value = objectsIntoArray($value, $arrSkipIndices);
            }
            if (in_array($index, $arrSkipIndices)) {
                continue;
            }
            $arrData[$index] = $value;
        }
    }
    return $arrData;
}

But in this objectsIntoArray() and json_encode() both are throwing function undefined errors. $retValue contains the xml data. I am not able to figure out why i am getting this error. Am i missing something. I am totally new to php and not much aware of it. Please help me regarding this.

Originally posted 2013-11-09 21:26:45.