title: Why (and when) do I need to use parentheses after sizeof?
body: <p>The below fails to compile:</p>
  
  <pre><code>typedef int arr[10];
  int main(void) {
      return sizeof arr;
  }
  
  sizeof.c:3: error: expected expression before ‘arr’
  </code></pre>
  
  <p>but if I change it to</p>
  
  <pre><code>sizeof(arr);
  </code></pre>
  
  <p>everything is fine. Why?</p>