Array indexing starting at a number not 0

Question

Is it possible to start an array at an index not zero...I.E. you have an array a[35], of 35 elements, now I want to index at say starting 100, so the numbers would be a[100], a[

Answer 1

I remember reading in the book 'Expert C Programming - Deep C Secrets', Peter Van der Linden discloses a trick to fool the compiler into thinking array offsets starts at 1...theoretically the trick can be accomplished, I do not have the book with me, but offhand, I recall reading it...it is not portable and may produce undefined behavior...

Edit: See here section 6.17 on the C-FAQ. WARNING: Not Portable and Undefined behavior! To quote from the source here.

6.17: Here's a neat trick: 
      if I write int realarray[10]; 
         int *array = &realarray[-1]; 
I can treat "array" as if it were a 1-based array. A: Although this technique 
is attractive (and was used in old editions of the book _Numerical Recipes in C_), 
it is not strictly conforming to the C Standard. Pointer arithmetic is defined 
only as long as the pointer points within the same allocated block of memory, 
or to the imaginary "terminating" element one past it; otherwise, the behavior 
is undefined, *even if the pointer is not dereferenced*. The code above could 
fail if, while subtracting the offset, an illegal address were generated 
(perhaps because the address tried to "wrap around" past the beginning of some 
memory segment). 

References: K&R2 Sec. 5.3 p. 100, Sec. 5.4 pp. 102-3, Sec. A7.7 pp. 205-6; 
ISO Sec. 6.3.6; Rationale Sec. 3.2.2.3.

Read more: http://www.faqs.org/faqs/C-faq/faq/#ixzz0ftyqHOvm

Hope this helps.