title: C pointer arithmetic without object of structure
body: <p>I think it is not possible in C but ask to verify this. Is it possible to make arithmetic between structure members without real variable of this type? For example:</p>
  
  <pre><code>typedef struct _s1
  {
    int a;
    int b;
    int c;
  } T1;
  </code></pre>
  
  <p>I want to see the offset of "c" member compared to structure beginning. It is easy if I have variable:</p>
  
  <pre><code>T1 str;
  
  int dist = (int)&amp;str.c - (int)&amp;str;
  </code></pre>
  
  <p>But my structure is too big and it has no member in RAM (only in EEPROM). And I want to make some address calculations but not to define RAM member. I can do the job with structure pointer instead of structure variable (it will cost only 4 bytes) but the case is interesting for me.</p>