Re: comparing data

[mfb@mbunix.mitre.org (Michael F Brenner)]

Well, maybe it can be done in one IF statement, but here is a 
solution that takes a few IF statements. 

Assuming that these three values are in a random access
container, one way to approach the problem of displaying 
the lowest value is as follow.

      type indexes is range 1..3;
      type values  is range 1 .. 1_000_000;
      package education is new links_on_a_chain (values, indexes);

      education.rtm(5); -- The first one is on the linked list
      education.rtm(1); -- The second value is on the linked list
      education.rtm(9284); -- The Third value is on the linked list
     
      -- The three values are in the container called education.
 
      if education.remember (1) >= education.remember(2) and
         education.remember (1) >= education.remember(3) then
         education.delete_fact (1); -- One is the biggest
      end if;

      if education.remember (2) >= education.remember(1) and
         education.remember (2) >= education.remember(3) then
         education.delete_fact (2); -- Two is the biggest
      end if;
      
      if education.remember (3) >= education.remember(1) and
         education.remember (3) >= education.remember(2) then
         education.delete_fact (3); -- Three is the biggest
      end if;
        
      -- At this point, the largest, and possibly the second
      -- largest element in the container has been deleted.

      if education.number_of_elements = 1 then
        text_io.put_line (values'image (education.arb));
        raise success;
      end if;

      education.effect_a_reorganization;

      -- At this point, there are two elements in the
      -- container, whose indexes are 1 and 2.    

      if education.remember (1) >= education.remember (2) then
        education.delete_fact (1);
      else
        education.delete_fact (2);
      end if;

      education.effect_a_reorganization;
 
      -- At this point, there is one element of the list.

      text_io.put (values'image (education.remember (1)));
      text_io.put_line ("is the smallest value");