问题是，由于键重复，您的数组无效，因为您怀疑.解决此问题的一种方法是将每个"RoomInfo"包装在自己的数组中，如下所示:

The problem is, your array is invalid as you suspected because of the duplicate keys. One way to solve the issue is to wrap each "RoomInfo" in its own array like so:

$param = array(
    "Destination" => $destcode,
    "HotelCityName" => $city,
    "HotelLocationName" => "",
    "HotelName" => "",
    "CheckIn" => date("Y-m-d", strtotime($checkin)),
    "CheckOut" => date("Y-m-d", strtotime($checkout)),
    "RoomsInformation" => array (
        array(
            "RoomInfo" => array(
                "AdultNum" => 2,
                "ChildNum" => 1,
                "ChildAges" => array(
                    "ChildAge" => array(
                        "age"=>11
                    )
                )
            ),
        ),
        array(
            "RoomInfo" => array(
                "AdultNum" => 1,
                "ChildNum" => 0,
                "ChildAges" => array(
                    "ChildAge" => array(
                        "age"=>0
                    )
                )
            )
        )
    ),
    "MaxPrice" => 0,
    "StarLevel" => 0,
    "AvailableOnly" => "false",
    "PropertyType" => "NotSet",
    "ExactDestination" => "false"
);

您可以像这样生成XML:

And you can generate the XML like this:

// create simpleXML object
$xml = new SimpleXMLElement("<?xml version=\"1.0\"?><SearchHotels></SearchHotels>");
$node = $xml->addChild('request');

// function call to convert array to xml
array_to_xml($param, $node);

// display XML to screen
echo $xml->asXML();
die();

// function to convert an array to XML using SimpleXML
function array_to_xml($array, &$xml) {
    foreach($array as $key => $value) {
        if(is_array($value)) {
            if(!is_numeric($key)){
                $subnode = $xml->addChild("$key");
                array_to_xml($value, $subnode);
            } else {
                array_to_xml($value, $xml);
            }
        } else {
            $xml->addChild("$key","$value");
        }
    }
}

我将array_to_xml函数归功于出色的作者: https://***.com/a/5965940/2200766

I attribute the array_to_xml function to the wonderful author here: https://***.com/a/5965940/2200766