CS 12 Assignment 3, part 1, Fall 2008
Adapted/extended from textbook's solutions package by cmc, 10/24/08

4.5 Review Questions 2, 3, and 4 

2. Information hiding occurs when program entities are declared and
   used locally within a function or module, preventing them from
   being seen and/or used outside the function or module.

3. Information hiding can promote ease of program modification by
   confining the region of program text in which changes have to be
   made to a local region of the total program text. When entities are
   defined locally within a function, or privately inside a module in its
   implementation file, then changes in the local or private entities
   can be made without interfering with entities outside.

4. A representation-independent notation is a notation which does
   not have to be changed when its underlying data representation is
   changed. For example, GetLink(N) is a representation-independent
   notation for getting the Link of node N in a linked-list, whereas the
   three expressions N->Link, ListMemory[N].Link, and Link[N] are
   representation-dependent notations (from which, by looking at
   the notations, one can discover what the underlying data
   representations are).

4.6 Review Questions 2, and 3

2. Procedural abstraction occurs when one creates a procedure, P( a1,
   a2, ..., an), as a named unit of action. Then, one can use the action
   represented by P, knowing only what P does and not how P is
   implemented. Later, one can change how P is implemented without
   changing every instance of P's use (which could not have happened
   if the instructions giving P's action had been repeated every time
   P was used). The use of procedural abstraction therefore promotes
   ease of use and change.

3. Data abstraction occurs when one hides the representation of a
   data structure and the implementation details of the operations
   on it using a representation-independent notation. This enables
   the abstract data to be used knowing only what it does, not how its
   details are implemented. As with procedural abstraction, so also
   with data abstraction, by separating the what from the how, both
   ease of use and ease of modification are promoted.

5.3 Review Questions 1, 2, and 3

1. Assertions are logical statements that specify conditions that
   must be true.

   Especially (not necessary for full credit) {
     (a) the conditions that hold before a program is executed,
     (b) the net effect achieved after executing a program, or
     (c) the state of affairs achieved inside a program at various
         intermediate points during its execution.
   }

2. The precondition describes the conditions that hold true before a
   program (or function) is executed.

3. The postcondition describes the conditions that hold true after a
   program (or function) is executed.

5.5 Review Question 1

Unit testing consists of testing individual functions in isolation to
see if they work on all expected classes of inputs. Integration
testing tests the coordinated execution of functions, acting
together in the context of the conditions expected for actual
system operations.