--- loncom/homework/caparesponse/caparesponse.c	2000/10/25 22:02:53	1.4
+++ loncom/homework/caparesponse/caparesponse.c	2000/11/29 00:29:43	1.5
@@ -27,8 +27,13 @@ int caparesponse_capa_check_answer(char
   p.sig_lbound = sig_lbound;
   p.sig_ubound = sig_ubound;
   strncpy(p.ans_fmt,ans_fmt,ANSWER_STRING_LENG-1);
-  strncpy(p.unit_str,unit_str,ANSWER_STRING_LENG-1);
-  p.ans_unit   = u_parse_unit(unit_str);
+  if (unit_str[0]!='\0') {
+    strncpy(p.unit_str,unit_str,ANSWER_STRING_LENG-1);
+    p.ans_unit   = u_parse_unit(unit_str);
+  } else {
+    p.unit_str[0]='\0';
+    p.ans_unit=NULL;
+  }
   p.calc       = calc;
 
   /* assign_id_list and assign_pts_list exist in capaGrammerDef.y */