title: PHP Parsing JSON for value of a key in multidimensional array
body: <p>I'm trying to parse JSON with PHP, but I'm having trouble as my array is multidimensional and I won't necessarily know the names of everything I'm looking for. What I want to do is get the ID of every single item in the JSON file. I've looked on here but the solutions I've found only work for one instance of a key or require you to know the key's value. To show you an example of what I want, here's my JSON.</p>
  
  <pre><code>{
     "products_and_categories":{
        "new":[
           {
              "category_name":"Jacket",
              "name":"Half Zip Windbreaker",
              "position":3,
              "sale_price":0,
              "image_url":"0/65030/Half_Zip_Windbreaker_Green_1365029293_cart_1365029294.jpg",
              "price":14800,
              "new_item":true,
              "detail_view_url":null,
              "id":1950
           },
           {
              "category_name":"Jacket",
              "name":"The North Face\u00ae/Supreme\u003Cbr\u003EReflective 3M\u00ae Mountain Parka",
              "position":0,
              "sale_price":0,
              "image_url":"0/65059/The_North_Face--r----s--Supreme_br_Reflective_3M--r--_Mountain_Parka_Red_1365029303_cart_1365029305.jpg",
              "price":49800,
              "new_item":true,
              "detail_view_url":null,
              "id":1951
           },
           {
              "category_name":"Hats",
              "name":"Rubber Logo Camp Cap",
              "position":29,
              "sale_price":0,
              "image_url":"0/64915/Rubber_Logo_Camp_Cap_Navy_1365029249_cart_1365029251.jpg",
              "price":4800,
              "new_item":true,
              "detail_view_url":null,
              "id":1947
           }
        ],
        "Hats":[
           {
              "category_name":"Hats",
              "name":"Rubber Logo Camp Cap",
              "position":29,
              "sale_price":0,
              "image_url":"0/64915/Rubber_Logo_Camp_Cap_Navy_1365029249_cart_1365029251.jpg",
              "price":4800,
              "new_item":true,
              "detail_view_url":null,
              "id":1947
           },
           {
              "category_name":"Hats",
              "name":"Enamel S 5-Panel",
              "position":34,
              "sale_price":0,
              "image_url":"0/63614/Enamel_S_5-Panel_Green_1362616033_cart_1362616034.jpg",
              "price":5400,
              "new_item":false,
              "detail_view_url":null,
              "id":1904
           },
           {
              "category_name":"Hats",
              "name":"Big Striped Beanie",
              "position":35,
              "sale_price":0,
              "image_url":"0/61745/Big_Striped_Beanie_Green_1362023179_cart_1362023181.jpg",
              "price":3200,
              "new_item":false,
              "detail_view_url":null,
              "id":1853
           }
        ],
        "Decks":[
           {
              "category_name":"Decks",
              "name":"Power, Corruption, Lies Cruiser",
              "position":46,
              "sale_price":0,
              "image_url":"0/62026/Power__Corruption__Lies_Cruiser_Black_1362023285_cart_1362023286.jpg",
              "price":6000,
              "new_item":false,
              "detail_view_url":null,
              "id":1861
           },
           {
              "category_name":"Decks",
              "name":"Bling Logo Deck",
              "position":47,
              "sale_price":0,
              "image_url":"0/62018/Bling_Logo_Deck_Platinum_1362023282_cart_1362023283.jpg",
              "price":4900,
              "new_item":false,
              "detail_view_url":null,
              "id":1860
           }
        ],
        "Sweatshirts":[
           {
              "category_name":"Sweatshirts",
              "name":"Heathered Crewneck",
              "position":11,
              "sale_price":0,
              "image_url":"0/63855/Heathered_Crewneck_Heather_Pink_1362616124_cart_1362616125.jpg",
              "price":11800,
              "new_item":false,
              "detail_view_url":null,
              "id":1914
           },
           {
              "category_name":"Sweatshirts",
              "name":"Checkered Pullover",
              "position":12,
              "sale_price":0,
              "image_url":"0/63826/Checkered_Pullover_Yellow_1362616113_cart_1362616114.jpg",
              "price":14800,
              "new_item":false,
              "detail_view_url":null,
              "id":1913
           }
        ]
     },
     "unique_detail_view_url_prefixes":[
  
     ],
     "sales_available":false,
     "unique_image_url_prefixes":[
        "http://d2flb1n945r21v.cloudfront.net/production/uploaded/style/"
     ]
  }
  </code></pre>
  
  <p>Now, my code works if I just want the ID of items in the new category, but what I want to achieve is to get the ID of every item in the whole JSON file. 
  Here's my code.</p>
  
  <pre><code>&lt;?php
  $content = json_decode($json);
  foreach($content-&gt;products_and_categories-&gt;new as $entry){
      echo $entry-&gt;id;
  }
  </code></pre>
  
  <p>It returns this :</p>
  
  <pre><code>1950
  1951
  1947
  </code></pre>
  
  <p>So how do I return the IDs for all of the other categories? Thank you for reading this.</p>