Newbie: lookup scm var from c by name

[Mike Gran]

How do I get a scm var back into c?  In the code below,
I would have thought that scm_c_lookup should work.
Why does the second case work, but, not the first?


  scm_c_eval_string("(define a 10)");

  // Case 1
  s = scm_c_lookup ("a");
  if (SCM_INUMP (s))
      printf("Case 1: %d\n", SCM_INUM(s));

  // Case 2
  s = scm_c_eval_string("a");
  if (SCM_INUMP (s))
      printf("Case 2: %d\n", SCM_INUM(s));

Thanks for your patience.