POLITEKNIK MALAYSIA

DFC1023
PROBLEM SOLVING & PROGRAM DESIGN
CHAPTER 2:
PROBLEM SOLVING METHODS
S U B TO P I C 2 . 2 : P R O G R A M M I N G L I F E
C YC L E ( P LC )

AT THE END OF THIS CHAPTER, STUDENTS
SHOULD BE ABLE TO:
Understand Problem solving concept
 Explain the phases in Programming Life Cycle
a. Specify the problem
b. Analyze the problem
c. Design the algorithm to solve the problem
d. Implement the algorithm
e. Test and verify the completed program
f. Maintain and update the program
g. Documentation

PROGRAMMING LIFE CYCLE
Programming Life Cycle:
A framework or discipline, which uses certain
techniques needed in computer programming
development.
Life Cycle:
Refers to the changes made from an
old to a new program (the cycle starts again).

PHASES IN PROGRAMMING LIFE CYCLE
SPECIFY THE
PROBLEM
ANALYZE THE
PROBLEM
DESIGN THE
ALGORITHM
IMPLEMENT
THE ALGORITHM
TEST AND
VERIFY
MAINTAIN AND
UPDATE THE
PROGRAM
DOCUMENTATION

PHASE 1 – SPECIFY THE PROBLEM
• studies the problem.
• investigate the need for possible software automation in the given
system.
• specific recommendations for the problem.
Purposes:
 to find the need and
 to define the problem that needs to be solved.
 identify the operators and
 formula need to be used

PHASE 2: ANALYZE THE PROBLEM
Purpose:
To describe in detail a solution to a problem and
information needed in solving the problem.
How?
Study and understand the problem.
Identify:
The needed input.
The required output.
The needed process. For example: scientific formula
or particular theories.

PHASE 2: ANALYZE THE PROBLEM
In most cases, the solution requires more than one program.
The analyze requirement step consist of three major task :
1. Review requirement – chart, diagram and report.
2. Meet with system analyst and user – enables the programmer to
understand the purpose of requirement from the user perspective.
3. Identify input, process, output and data component. – use IPO chart.
Programmer review the content of IPO Chart with system analyst and
user. This allows programmers to be sure they completely understand
the purpose of the program.

PHASE 3: DESIGN THE ALGORITHM
Definition:
It is a framework or flow that shows the steps in
problem solving.
Methods to design a program:
1. Algorithm
2. Flowchart
3. Pseudo code

1. Algorithm
• Algorithm is a sequence of instructions to solve a
problem, written in human language, and it can solve
any problems when it is used with the correct
procedure.
• Example:
1. Get Input 3 numbers
2. Total up the 3 numbers using formula:
Total = number1 + number2 + number3
3. Calculate average 3 number using formula;
Average = (number1 + number2 + number3)/3
4. Display Total, Average

2. Flowchart
 A graphical representation of data, information and
workflow using certain symbols that are connected to
flow lines to describe the instructions done in problem
solving.
 It shows the flow of the process from the start to the
end of the problem solving.

2. Flowchart
Basic
Flowchart
symbol:

3. Pseudo code
 Steps in problem solving that is written half in
programming code and half in human language.
 Example:
START
Input number1, number2, number3;
Total = number1 + number2 + number3;
Average = (number1 + number2 + number3)/3
Display Total, Average;
END

PHASE 4: IMPLEMENT THE ALGORITHM
Definition: Writing problem solving into certain programming language such as C,
COBOL and others.
Problem solving: Instructions before it is coded into programming language.
Purpose: To produce a program to develop a system

PHASE 4: IMPLEMENT THE ALGORITHM
o Example:

PHASE 5: TEST AND VERIFY THE PROGRAM
o Testing: Using a set of data to discover errors and
to ensure accuracy of the program.
o Diagram indicates the process of testing:

 Debug: Debugging is a process of identifying and
correcting error.
o Three types of error:
oSyntax error (grammatical error)
oRuntime error
oLogic error

1. Syntax error (grammatical error)
 Occurs when the rules of programming language are not
applied.
 Correction is done during the program coding.
 The bug can be traced during the compilation.
 Also known as compile-time error.
 Must be corrected before executing and testing the program.

2. Run time error
 Occur when a program with no syntax error asks the computer to do something that
the computer is unable to reliably do.
 Example:
 trying to divide by a variable that contains a value zero
 trying to open a file that does not exists
3. Logic error
 Cannot be traced by compiler.
 Corrected during the problem solving process.
 Example output for average is 4, but when it runs, the output is 2.

PHASE 6: MAINTAIN AND UPDATE THE PROGRAM
Activity that verifies whether the operational system is performing as planned or an
activity to modify the system to meet the current requirement.
The process of changing a system after it has been applied to maintain its ability. The
changes may involve simple changes such as error correcting.

PHASE 6: MAINTAIN AND UPDATE THE PROGRAM
How to maintenance?
 Testing – Test the ability of the system.
 Measurement – Access data time. Example, time to save, print and others.
 Replacement – Replace the old system to new system.
 Adjustment – Adding needs to new system.
 Repair – For example: An old system cannot update the new data
 Updating – Update the database.

PHASE 7: DOCUMENTATION
 Definition:
A written or graphical report of the steps taken
during the development of a program.
 Purpose:
It will be useful in the future, in case of
modification or maintenance.

PHASE 7: DOCUMENTATION
Content of documentation:
 Description of the program.
 Specification of program requirement
 Program design such as pseudo code and flowchart
 List of program and comments (to explain about the program).
 Test results.
 User’s manual book.
 Program capabilities and limitation.

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