1. CS3369 Realtime Control Computer Software/DENG Xiaotie
Lecture 11. Design, Testing
and Documentation
11.1 Designing Issues
11.2 Debugging
11.3 Testing
11.4 Checking
11.5 Documentation
4/16/2019
CS3369 Realtime Control Computer Software/DENG Xiaotie

2. CS3369 Realtime Control Computer Software/DENG Xiaotie
Designing
Top-down Design in OOP
Data abstraction
classes and objects
member functions
hide data as private
Polymorphism
allow commonly used member functions to have the same name but perform according to class of an object
4/16/2019
CS3369 Realtime Control Computer Software/DENG Xiaotie

3. CS3369 Realtime Control Computer Software/DENG Xiaotie
OO Programming with C++
Top-down Design:
break tasks down into subtasks and write a function for each
make it easy for a team to work on large software projects
Functional abstraction: function as a black box so users only need to look at the function prototype and comments to use the function.
Function prototype tells programmers pre-conditions and post conditions for arguments(parameters) to function.
4/16/2019
CS3369 Realtime Control Computer Software/DENG Xiaotie

4. CS3369 Realtime Control Computer Software/DENG Xiaotie
Design of the Elevator
Functions to use
showelevator() //show elevator include the door .
//pre-conditions: there is no input. The inputs are the member variables of the class. door --decides the wide of the gap. Door=25 if the door is closed. Door =3 if the door is open. The process of opening a door is the process of changing the value of door. Other required variables, k-- the vertical position of the elevator. Position--the h-position of the elevator.
///post-conditions: the elevator is drawn.
4/16/2019
CS3369 Realtime Control Computer Software/DENG Xiaotie

5. CS3369 Realtime Control Computer Software/DENG Xiaotie
Design of the Elevator
Functions to use
erease() // erease the elevator. Draw black lines just for the door and the elevator, not for the skeleton. //pre-conditions are the same as selevator(). //post-conditions: door is ereased.
Stop() //stop will control the door to stop step by step. //pre-conditions: k--the vertical position and s--stands for if the door is really stopped. (both k and s are member variables.)
//post-condition: k and s may be changed. Stop() will be called many times. A door will be closed automatically once s==1. To this this, is simple, door=door-1.
4/16/2019
CS3369 Realtime Control Computer Software/DENG Xiaotie

6. CS3369 Realtime Control Computer Software/DENG Xiaotie
Design of the Elevator
Functions to use
close()// to change the value of door to close the door step by step. //pre-conditions: the value of door in used, a member variable close is used. Close ==0 if the door is not completely closed. Close ==1 if the door is completely closed. //post-conditions: the value of door is changed if the door is not completely closed. The value of door is not changed if the door is completely closed and close is set to be 1.
4/16/2019
CS3369 Realtime Control Computer Software/DENG Xiaotie

7. CS3369 Realtime Control Computer Software/DENG Xiaotie
Design of the Elevator
The main function
test if the elevator need to be stopped
if yes, call stop()
test if the elevator need to move
if yes, (a) call close(), and then change the position oof the elevator, i.e., k=k-1 or k=k-1.
Selevator();
delay(300);
erease();
repeat
4/16/2019
CS3369 Realtime Control Computer Software/DENG Xiaotie

8. CS3369 Realtime Control Computer Software/DENG Xiaotie
OO Programming with C++
ADT: abstract data types: programmer using the data type does not have access to details of how the values and operations are implemented.
interface:how to use ADT (for user)
implementation: how the interface is is realized as C++ code.
tips: hide member variables as private
access functions to access necessary data.
4/16/2019
CS3369 Realtime Control Computer Software/DENG Xiaotie

9. CS3369 Realtime Control Computer Software/DENG Xiaotie
Programming Practice
Art ? Science?
Programming languages change all the time, focusing on different aspects of programming techniques.
Even Experts do not agree on details of programming style. E.g.,
How to pair up parenthesis {}? Do we line them up on the same column? Do we indent every pair which encloses an inner loop.
4/16/2019
CS3369 Realtime Control Computer Software/DENG Xiaotie

10. CS3369 Realtime Control Computer Software/DENG Xiaotie
Programming Practice
Criteria:
reliable
maintainable
user friendly
re-usability
Good programming techniques are language independent. However, OO Languages provide useful tools to make it easier.
4/16/2019
CS3369 Realtime Control Computer Software/DENG Xiaotie

11. CS3369 Realtime Control Computer Software/DENG Xiaotie
Readability and comprehensibility
Naming
named entities in programs:
constants, variables, classes, objects, functions, files
use meaningful names:
names of objects should be closely related to the corresponding real world entities
use more than one word, upper and lower case, delimiter characters
avoid: ambiguities, cryptic abbreviations, unrelated names, single-letter identifies
4/16/2019
CS3369 Realtime Control Computer Software/DENG Xiaotie

12. CS3369 Realtime Control Computer Software/DENG Xiaotie
Readability and comprehensibility
Divide Program into logically meaningful groups:
class/object: for logically related entities
functions: important/related pieces of program
files: related functions and classes.
Write pre-conditions and post-conditions in comments for function prototypes/function bodies.
4/16/2019
CS3369 Realtime Control Computer Software/DENG Xiaotie

13. CS3369 Realtime Control Computer Software/DENG Xiaotie
Readability and comprehensibility
Use indentations (consistently and correctly) to indicate program structures
Use header file to
define classes and prototype member functions
store constants and global variables
Use Makefile to compile programs in different files and organize team project.
4/16/2019
CS3369 Realtime Control Computer Software/DENG Xiaotie

14. CS3369 Realtime Control Computer Software/DENG Xiaotie
Debugging/Testing/Checking
Debugging: Try to locate errors:
Grammar Errors:
Run Time Errors:
Testing: Searching for errors.
developer tests (gently) for delivery of good product.
expert tester tries to break product for quality guarantee.
Checking: Make sure the output for an input is OK
an extra function accompanying a function which checks for correctness of the output for every run of the function.
4/16/2019
CS3369 Realtime Control Computer Software/DENG Xiaotie

15. CS3369 Realtime Control Computer Software/DENG Xiaotie
Debugging
Grammar Errors: Usually a good programming language comes with compiler tools which locate (usually the first occurrence of) errors.
Run Time Errors.
Tools in Turbo C:
trace: statements are executed line by line
break point: execution stops at the line a break point is set
Print-out statements: print out values of certain variables to see if execution goes as expected
4/16/2019
CS3369 Realtime Control Computer Software/DENG Xiaotie

16. CS3369 Realtime Control Computer Software/DENG Xiaotie
Debugging: An Example
original function:
int summation(int x, int y) {
int z;
z=x-y;
return z}
printout statements added to DEBUG:
int z; cout<<“x=“ <<x<< “y=“ <<y<<endl;
z=x-y; cout << “z=“ << z;
4/16/2019
CS3369 Realtime Control Computer Software/DENG Xiaotie

17. CS3369 Realtime Control Computer Software/DENG Xiaotie
Testing
Testing process:
top-down testing
bottom-up testing
real-time thread testing
White Box Testing: knowing all codes and apply path testing
exhaustive testing: make sure all paths are executed at least once
selective testing: chooses some paths to test
Black Box Testing: compare the output of the program with the expected output for many inputs.
4/16/2019
CS3369 Realtime Control Computer Software/DENG Xiaotie

18. CS3369 Realtime Control Computer Software/DENG Xiaotie
Testing Process
Top-down testing: usually for functionality
Test in order of top level system, sub-system, module...
Bottom-up testing
test functions at the lowest level and work up hierarchy
Real-time thread testing
real time systems consist of co-operating processes and maybe interrupt driven
external events may cause control transfers.
thread testing identifies and executes each possible thread (of control flow of processes.)
4/16/2019
CS3369 Realtime Control Computer Software/DENG Xiaotie

19. CS3369 Realtime Control Computer Software/DENG Xiaotie
Input Data for Testing
Choose input data according to the empirical distribution
Choose degenerated patterns of data
For the example of sorting function:
all data are the same value
input of size 0/1/2
Choose simple patterns of data
input already sorted
input are reversals of a sorted list
4/16/2019
CS3369 Realtime Control Computer Software/DENG Xiaotie

20. CS3369 Realtime Control Computer Software/DENG Xiaotie
Checking
Make sure the output for an input is OK
Write a checker function accompanying a function which checks for correctness of the output
Invoke the checker function for every run of the original function.
For the sorting function as an example: write an function to check the output of the sorting function is indeed sorted and check if the output data are the same as the input data
4/16/2019
CS3369 Realtime Control Computer Software/DENG Xiaotie

21. CS3369 Realtime Control Computer Software/DENG Xiaotie
An Example for Checking
sort(A,n)
{old_sort(A,n); //input is an array A of size n and output //is in the same array A but sorted.
if (!check(A,n)) report-error();}
int check(A,n) {
int I;
if (n==1) return TRUE;
for (I=0; I<n-1; I++) {
if A[I]>A[I+1] return FALSE;}
return TRUE; } //here we only check A is sorted. In reality //we need also check the output array contains the same //set of elements as the input.
4/16/2019
CS3369 Realtime Control Computer Software/DENG Xiaotie

22. CS3369 Realtime Control Computer Software/DENG Xiaotie
An Example for Checking
max(A,n)
{int tmp;
tmp=old_max(A,n);
if (!checkmax(tmp,A,n)) report-error();}
int check(int a, int A[], int n) {
int I;
if (n==1) return TRUE;
for (I=0; I<n-1; I++) {
if A[I]>a return FALSE;}
return TRUE; }
4/16/2019
CS3369 Realtime Control Computer Software/DENG Xiaotie

23. CS3369 Realtime Control Computer Software/DENG Xiaotie
Another Example for Global Variables
The roots of a quadric equation ax2+bx+c=0 are
x1= (-b+( b2-4ac))/2ac
x2=x1= (-b- ( b2-4ac))/2ac
include<iostream.h>
float x1, x2;
int flag=0;
void roots(float a, float b, float c)
void main(void) {
roots(1.0,2.0, 1.0);
if(flag == 0)
cout<<“The roots are”<<x1<<x2;
else
cout<<“No real root”; }
void roots(float a, float b, float c) {
if (b*b-4*a*c>=0)
x1=(-b+sqrt(b*b-4*a*c))/(2*a*c);
x2 =(-b-sqrt(b*b-4*a*c))/(2*a*c); }
else
flag=1;
x1, x2 and flag are used as global variables. Otherwise, roots must return two values that we do not know how to do it.
4/16/2019
CS3369 Realtime Control Computer Software/DENG Xiaotie

24. CS3369 Realtime Control Computer Software/DENG Xiaotie
More about Equation
Write a function that returns two roots of an equation
ax2 +bx +c =0.
Write a function that checks if the roots a correct.
4/16/2019
CS3369 Realtime Control Computer Software/DENG Xiaotie

25. CS3369 Realtime Control Computer Software/DENG Xiaotie
Documentation: Description of control software system
functional specification
design specification
system manuel:
for system maintenance people
detailed description of system structure/component
user manuel
how system is to be operated
written at the level of expertise of the operator
system integration tests and test results:
4/16/2019
CS3369 Realtime Control Computer Software/DENG Xiaotie

26. Does it kill some stones?
Flow Chart
Beginning of game:
display the board
Player 2’s next move
Display the new board
yes no
Player 1’s next move
Does it kill some stones?
resign
End of the Game
Display the new move
Choose a move
yes no
Note: only flow chart of
player 1 is displayed and
that of player 2 is similar.
Is it legal
4/16/2019
CS3369 Realtime Control Computer Software/DENG Xiaotie