Software engineering

Software Engineering .
Software Engineering
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These two statements
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else if (b) x =
2; else x = 0;
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= 2; else x =
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statements then use
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statements then use
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> 10) {
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statements then use
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2;
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10)
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else
printf(“a
is greater than
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brackets (blocks)
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> 10) {
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= 0;
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address =
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(uint32_t)&a);
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= a;
}
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2;
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else x = -2;
if (a < 10)
if (a < 10)
printf(“a is less
else if (a == 10)
else if (a == 10)
printf(“a is
else
else
printf(“a is
if (a < 4 && b > 10) {
if (a < 4 && b > 10) {
c = a * b; b = 0;
}
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(b) x = 2; else x = 0;}
printf(“a is less
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= -2;
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printf(“a is
(uint32_t)&a);
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}
c = a * b; b = 0;
c = a + b; b = a;
equivalent:
equivalent:
Is this correct?
(b) x = 2; else x = 0;
(b) x = 2; else x = 0;}
(a) x = 3; else {(b) x = 2; else x = Is this correct?
(b) x = 2;
= -2;
if (a < 10)
printf(“a is less
else if (a == 10)
printf(“a is
else
printf(“a is
if (a < 4 && b > 10) c = a * b; b = 0;
}
c = a + b; b = a;
(b) x = 2; else x = if if (a) x = 3; else if
(b) x = 2;
else (z) x = 0; else
= -2;

• Lecturer – Ms Hasanthi Dahanayake,
• Student Name – G.M.D.Nuwansiri,
• Subject – Information Technology,
• Register No – SIBA/BABL/12-44,
• Institution – SIBA Campus,
• March 20/2014.
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. . .

Content.
• Introduction.
• Software Engineering.
• Software Products.
• Software Product Attributes.
• Importance of Product Characteristics.
• The Software Process.
• Engineering Process Model.
• Software Engineering is Different.
• Software Process Models.
• Process Model Problems.
• Model Advantages.
• Conclusion.
Software Software Software Software Software • Introduction.
• Introduction.
• Introduction.
• Introduction.
• Introduction.
• Introduction.
• Introduction.
• Introduction.
• Introduction.
• Introduction.
• Introduction.
• Introduction.
• Introduction.
• Introduction.
• Introduction.
• Introduction.
• Introduction.
• Introduction.
• Introduction.
• Introduction.
• Introduction.
• Introduction.
• Introduction.
• Introduction.
• Introduction.
• Introduction.
• Introduction.
• Introduction.
• Software Product • • Engineering Process Model.
• Software • • Importance of Product • • Importance of Product Characteristics.
• Software Product • Importance of Product • • Importance of Product Characteristics.
Software • The Software Process.
• Software Product • • Engineering Process Model.
Importance of • • Importance of Product Characteristics.
The Software Process.
Software • • Engineering Process Model.
Importance • • Importance of Product Characteristics.
• Conclusion.
• Engineering Process • • Process Model Problems.
Importance • • Importance of Product Characteristics.
• Conclusion.
• Software Engineering • • Model Advantages.
• Conclusion.
The Software • • Software Process Models.
• Conclusion.
• Conclusion.
• Engineering Process • Software Engineering • • Model Advantages.
• Conclusion.
• Conclusion.
The Software • Software Process Models.
Engineering • • Process Model Problems.
• Conclusion.
• Conclusion.
Software Engineering • Software Process Models.
Engineering • • Process Model Problems.
• Conclusion.
Software Engineering • • Model Advantages.
Software Process • • Process Model Problems.
• Conclusion.
• Conclusion.
• Conclusion.
• Conclusion.
• Conclusion.
• Introduction.
• Conclusion.
• Conclusion.
Software • • Model Advantages.
• Conclusion.
Software Process • Process Model • • Model Advantages.
• Conclusion.
• Conclusion.
• Conclusion.
• Conclusion.
• Conclusion.
• Introduction.
• Conclusion.
• Conclusion.
Software • • Conclusion.
Process Model • Model Advantages.
• Conclusion.
Process • Model Advantages.
• Conclusion.
Model Advantages.
• Conclusion.
• Conclusion.

Introduction.
/* you generally want to
* include stdio.h and
* stdlib.h
* */
#include <stdio.h>
#include <stdlib.h>
int main (void)
{
int main (void)
{
}
printf(“Hello Worldn”);
exit(0);
* stdlib.h
* */
#include <stdio.h>
#include <stdlib.h>
exit(0);
}
* stdlib.h
* */
#include <stdio.h>
#include <stdlib.h>
int main (void)
{
int main (void)
{
}
exit(0);
* stdlib.h
* */
#include <stdio.h>
#include <stdlib.h>
exit(0);
}
* stdlib.h
* */
#include <stdio.h>
#include <stdlib.h>
int main (void)
{
int main (void)
{
}
exit(0);
* stdlib.h
* */
#include <stdio.h>
#include <stdlib.h>
exit(0);
}
* stdlib.h
* */
#include <stdio.h>
#include <stdlib.h>
int main (void)
{
int main (void)
{
}
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* stdlib.h
* */
#include <stdio.h>
#include <stdlib.h>
exit(0);
}
* stdlib.h
* */
#include <stdio.h>
#include <stdlib.h>
int main (void)
{
exit(0);
}
* stdlib.h
* */
#include <stdio.h>
#include <stdlib.h>
* stdlib.h
* */
#include <stdio.h>
#include <stdlib.h>
* stdlib.h
* */
#include <stdio.h>
#include <stdlib.h>
* stdlib.h
* */
#include <stdio.h>
#include <stdlib.h>
* stdlib.h
* */
#include <stdio.h>
#include <stdlib.h>
* stdlib.h
* */
#include <stdio.h>
#include <stdlib.h>
* stdlib.h
* */
#include <stdio.h>
#include <stdlib.h>
* stdlib.h
* */
int main (void)
#include int {
<main stdio.(h>
void)
#{
include <stdlib.h>
int main (void)
{
int main (void)
{
exit(0);
int main (void)
{
int main (void)
{
exit(0);
int main (void)
{
exit(0);
int main }
(void)
{
exit(0);
}
exit(0);
}
exit(0);
}
exit(0);
}
exit(0);
}
* stdlib.h
* */
#include <stdio.h>
#include <stdlib.h>
}
* }
include stdio.h and
* stdlib.h
* */
#include <stdio.h>
#include <stdlib.h>
int main (void)
{
int main (void)
{
exit(0);
}
exit(0);

• Software Engineering is the science and art of
building significant software systems that are:
1) on time
2) on budget
3) with acceptable performance
4) with correct operation.
Software
Engineering Software
Engineering
Software
Engineering
Software
Engineering
Software
Engineering
Software
Engineering

• The economies of all developed nations are
dependent on software.
• More and more systems are software controlled.
• Software engineering is concerned with theories, methods and
tools for professional software development.
• Software engineering expenditure represents a
significant fraction of developed countries.

Software Products
• Generic products:
• Stand-alone systems which are produced by a development organization and
sold on the open market to any customer.
• Customized products:
• Systems which are commissioned by a specific customer and developed
specially by some contractor.

Software Product Attributes.
• Maintainability
• Dependability
• Efficiency
• Usability
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import java.util.*;
import java.awt.*;
import java.util.*;
import java.awt.*;
import java.util.*;
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. . .
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import java.util.*;
{
. . .
}
{
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}
{
. . .
}
{
. . .
}
{
. . .
}
{
. . .
}
{
. . .
}
{
. . .
}

Importance of Product Characteristics.
• The relative importance of these characteristics depends on the
product and the environment which is to be used.
• In some cases, some attributes may dominate
• In safety-critical real-time systems, key attributes may be dependability
and efficiency.
import java.awt.*;
import java.util.*;
import java.awt.*;
import java.util.*;
import java.awt.*;
import java.util.*;
import java.awt.*;
import java.util.*;
import java.awt.*;
import java.util.*;
{
. . .
}
{
. . .
{
. . .
{
{

• Structured set of activities required to develop a
software system
• Specification
• Design
• Validation
• Evolution
• Activities vary depending on the organization
and the type of system being developed.
• Must be open modeled if it is to be
managed.
for (i = 0; i < MAXVALUE;
i++) {
dowork();
}
while (c != 12) {
dowork();
}
do {
dowork();
} while (c < 12);
Software Software Software Software Software Software

Engineering Process Model.
• Specification: Set out the requirements and
constraints on the system.
• Design: Produce a model of the system.
• Manufacture: Build the system.
• Test: Check the system meets the required
specifications.
• Install: Deliver the system to the customer and
ensure it is operational.
• Maintain: Repair errors in the system as they
are discovered.

Software Engineering is Different.
• Normally, specifications are incomplete.
• Very blurred distinction between specification,
design and manufacture.
• No physical realization of the system for testing.
• Software does not wear out - maintenance
does not mean component replacement.
class Person {
String name;
int age;
void birthday ( ) {
age++;
System.out.println (name +
' is now ' + age);
}
}
class Person {
String name;
int age;
void birthday ( ) {
age++;
' is now ' + age);
}
}
class Person {
String name;
int age;
void birthday ( ) {
age++;
' is now ' + age);
}
}
class Person {
String name;
int age;
void birthday ( ) {
age++;
' is now ' + age);
}
}
class Person {
String name;
int age;
void birthday ( ) {
age++;
System.out.println (name ' is now ' + age);
}

Software Process Models.
• Waterfall
• Separate and distinct phases of specification and development
• Evolutionary
• Specification and development are interleaved
• Formal Transformation
• A mathematical system model is formally transformed to an implementation
• Reuse-based
• The system is assembled from existing components

Process Model Problems.
• Waterfall
• High risk for new systems because of specification and
design problems.
• Low risk for well-understood developments using familiar
technology.
• Prototyping
• Low risk for new applications because specification and
program stay in step.
• High risk because of lack of process visibility.
• Transformational
• High risk because of need for advanced technology and
staff skills.

Model Advantages.
• Focuses attention on reuse options.
• Focuses attention on early error elimination.
• Puts quality objectives up front.
• Integrates development and maintenance.
• Provides a framework for hardware/software
development.
#define QINSERT_BEFORE(loc, node, field)
do {
*(loc)->field.prev = (node);
(node)->field.prev =
(loc)->field.prev;
(loc)->field.prev =
&((node)->field.next);
(node)->field.next = (loc);
} while (/* */0)
#define QINSERT_AFTER(loc, node, field)
do {
((loc)->field.next)->field.prev =
&(node)->field.next;
(node)->field.next = (loc)->field.next;
(loc)->field.next = (node);
(node)->field.prev = &(loc)->field.next;
} while ( /* */ 0)
#define QREMOVE(node, field)
do {
*((node)->field.prev) = (node)->field.next;
((node)->field.next)->field.prev =
(node)->field.prev;
(node)->field.next = (node);
(node)->field.prev = &((node)->field.next);
} while ( /* */ 0)

Conclusion.
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Be Creative….
Be Creative….
Be Creative….
Be Creative….
Be Creative….
Be Creative….
Be Creative….
Be Creative….
Be Creative….
Be Creative….
Be Creative….
Be Creative….
Be Creative….
Be Creative….
Be Creative….
Be Creative….
Be Creative….
Be Creative….
Be Creative….
Be Creative….
Be Creative….
Be Creative….
Be Creative….
Be Creative….
Be Creative….
Be Creative….
Be Creative….
Be Creative….
Be Creative….
Be Creative….
Be Creative….
Be Creative….
Be Creative….
Be Creative….
Be Creative….
Be Creative….
Be Creative….
Be Creative….
Be Creative….
Be Creative….
Be Creative….
Be Creative….
Be Creative….
Be Creative….
Be Creative….
Be Creative….
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Be Creative….
BBee CCrreeaattiivvee……..Be Creative….

Software engineering

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