未定义的索引：HotelImages - Expedia

I have the following snippet, taken from http://developer.ean.com/docs/hotel-info/examples/rest-default-content

[ "HotelImages": {
            "@size": "16",
            "HotelImage": [
                {
                    "hotelImageId": 4694179,
                    "name": "",
                    "category": 1,
                    "type": 0,
                    "caption": "Exterior",
                    "url": "/hotels/1000000/10000/5900/5900/5900_44_b.jpg",
                    "thumbnailUrl": "/hotels/1000000/10000/5900/5900/5900_44_t.jpg",
                    "supplierId": 13,
                    "width": 350,
                    "height": 350,
                    "byteSize": 0
                },
                {
                    "hotelImageId": 4694182,
                    "name": "",
                    "category": 2,
                    "type": 0,
                    "caption": "Lobby",
                    "url": "/hotels/1000000/10000/5900/5900/5900_47_b.jpg",
                    "thumbnailUrl": "/hotels/1000000/10000/5900/5900/5900_47_t.jpg",
                    "supplierId": 13,
                    "width": 350,
                    "height": 350,
                    "byteSize": 0
                }, ]

How can get the data of url? It's actually a URL which we should append with http://images.travelnow.com/

Example : echo $data['HotelImages']['HotelImage']['url'];

But it gives me the following error

undefined index : HotelImages

How can I resolve this?

Correct your JSON sytax and try

 $data ='{"HotelImages": {
            "@size": "16",
            "HotelImage": [
                {
                    "hotelImageId": 4694179,
                    "name": "",
                    "category": 1,
                    "type": 0,
                    "caption": "Exterior",
                    "url": "hxxp://media.expedia.com/hotels/1000000/10000/5900/5900/5900_44_b.jpg",
                    "thumbnailUrl": "hxxp://media.expedia.com/hotels/1000000/10000/5900/5900/5900_44_t.jpg",
                    "supplierId": 13,
                    "width": 350,
                    "height": 350,
                    "byteSize": 0
                },
                {
                    "hotelImageId": 4694182,
                    "name": "",
                    "category": 2,
                    "type": 0,
                    "caption": "Lobby",
                    "url": "hxxp://media.expedia.com/hotels/1000000/10000/5900/5900/5900_47_b.jpg",
                    "thumbnailUrl": "hxxp://media.expedia.com/hotels/1000000/10000/5900/5900/5900_47_t.jpg",
                    "supplierId": 13,
                    "width": 350,
                    "height": 350,
                    "byteSize": 0
                }]}}';

    $k =  json_decode($data); 
    print_r($k->HotelImages->HotelImage[0]->url); 
    exit();