title: json_decode to associative array whilst preserving datatypes of the keys
body: <p>Given this simple json object:</p>
  
  <pre><code>{
    "100": 0,
    "100T": 0
  }
  </code></pre>
  
  <p>How do I decode it to an associate array such that both the keys "100" and "100T" remain as strings. When I use json_decode the "100" is converted to an integer.</p>
  
  <p>Example code:</p>
  
  <pre><code>$json = '{"100":0, "100T":0}';
  $array = json_decode($json, true);
  var_dump($array);
  </code></pre>
  
  <p>Gives this output:</p>
  
  <pre><code>array(2) {
    [100] =&gt;
    int(0)
    '100T' =&gt;
    int(0)
  }
  </code></pre>
  
  <p>But I want this output instead:</p>
  
  <pre><code>array(2) {
    '100' =&gt;
    int(0)
    '100T' =&gt;
    int(0)
  }
  </code></pre>
  
  <p>I'm using PHP version 7.0.25 on Ubuntu 16.04</p>