Programming fundamentals 2

Tutor: Bilal Janjooa Assistant Professor
The University of Lahore
MS Telecom. Eng. From The University of Sunderland UK
1Bilal Janjooa bilal.janjooa@yahoo.co.uk

Lecture No. 2

Outline
 A computer is a useful tool for solving a great variety of
problems.
 To make a computer do anything (i.e. solve a problem),
we have to write a computer program.
 In a computer program we tell a computer, step by
step, exactly what want to do.

What is program
“A precise sequence of steps to
solve a particular problem”

 Following each step mechanically, to accomplish the
end goal.
 The sequence of steps to be performed in order to
solve a problem by the computer is known as an
algorithm.
 Flowchart is a graphical or symbolic representation of
an algorithm. It is the diagrammatic representation of
the step-by-step solution to a given problem.

Concept of Languages
Languages are used for
Communication between Users and
Computers.

Program Design Process
 Program Design consists of the steps a programmer
should do before they start coding the program in a
specific language. Proper program design helps other
programmers to maintain the program in the future.

Problem Solving is easy if you
follow these steps
Understan
d
the
problem

Step 1 – Understand the problem
Read the problem carefully.
Find the important information.
Write down the numbers.
Identify what the problem wants
you to solve.
Ask if your answer is going to be
a larger or smaller number
compared to what you already
know. 10Bilal Janjooa bilal.janjooa@yahoo.co.uk

Step 1 - Understand the Problem
Read the problem carefully.
Ahmed earned 14 Reading
points the first week of
November. At the end of the
following week he had a total of
31 points. How many points did
he earn the second week?

Find the important information.
Ahmed earned 14 Accelerated
Reading points the first week of

Write down the numbers.
Total = 31 1st week =14

Identify what the problem wants
you to solve.
2nd week = 14Bilal Janjooa bilal.janjooa@yahoo.co.uk

Ask if your answer is going to be a
larger or smaller number compared
to what you already know.
2nd week =
?It will be smaller than the total but
may or may not be smaller than
the first week.

follow these steps
Decide
how
you’re
going to
solve the
problem

Step 2 - Decide how you’re going to
solve the problem
Choose a method
Use a graph Use formulas
Write an equation Make a list
Find a pattern Work backwards
Use reasoning Draw a picture
Make a table Act it out

solve the problem
Write your equation
Since I know both weeks total 31 I write
14 + s = 31
2nd week =
?

solve the problem
Write your equation
I can use the inverse operation to solve for s
14 + s = 31 31 – 14 = s
2nd week =
?

follow these steps
Solve
The
Problem

Step 3 - Solve the problem
3 1
– 1 4
2nd week =
? 2
1
71 21Bilal Janjooa bilal.janjooa@yahoo.co.uk

follow these steps
Look
Back &
Check

Step 4 - Look Back & Check
Reread the problem
Luis earned 14 Accelerated

Substitute your new number
Reading points the first week
of November. At the end of
the following week he had a
total of 31 points. How many
points did he earn the second
week?
2nd week = 17

Substitute your new number
week?
14 + 17 = 31

Did your new number work?
week?
14 + 17 = 31 Yes!

Program Design Phases
 Program Design Process Include:
 Problem Solving Phase
 Implementation Phase

Problem Solving Phase
 Problem solving is a skill which can be developed by
following a well organized approach.
 Programming is also a problem solving activity.
 Programmer use software development method to
solve problems.

Software development activities
 The following steps can be followed to solve any kind
of problem:
1. Problem Identification
2. Specify Requirements
3. Analyze Problem
4. Design algorithm and draw flowchart
5. Write the program (Coding)
6. Testing and Debug the program
7. Implement the program
8. Maintain and Update the program
9. Document the program

Problem Identification
 At this stage the problem being solved is observed
carefully.
 Major area of concern are identified.
 Irrelevant information is filter out.

Specify Requirements
 This stage demands to make clear the user’s
requirements so that a proper solution could be
suggested.
 Requirements are documented here.

Analyze the problem
 Problem is decomposed into sub-problems.
 This lead to simple solution
 The technique is known is top down design (also
called divide and conquer(overcome) rule ).
 To approach the right solution we may ask certain
questions:-
i. How many solutions are there to the given problem?
ii. Which one is the best solution?
iii. What are the input and output?
iv. How can the bigger problem be divided into sub
problems?

Design Algorithm and draw
Flowchart
 Designing the algorithm requires to develop a finite
list of steps to solve a problem.
 Once algorithm has been designed it should be
verified through desk checking.
 Desk Checking is the process of carefully observing the
working of an algorithm, on the paper, for some test data.
 After designing the algorithm, the next step is to draw
a flowchart.
 Flowchart in fact, maps the algorithm to a pictorial
presentation which helps in understanding the flow of
control and data in algorithm.

Write the Program (Coding)
 Coding involves the conversion of an algorithm to
a program, written in any programming language.
 The programmer must know the syntax of the
programming language chosen.
 The grammatical rules of a programming language
to write programs are referred to as syntax of that
programming language.

Test and Debug the program
 Testing requires evaluating the program to verify that
it works as desired.
 Debugging is the process of finding and removing
errors in the program.

 There can be three types of errors:-
 Syntax Errors:-
 Occur when program violates one or more grammatical
rules of the programming language.
 Usually detected at compile time by the compiler.
 There can be many reasons such as typing wrong
commands or program statements.

 Logical Errors:-
 Logical errors occur when program follow a wrong logic.
 The translator (compiler or interpreter) does not report
any error message for a logical errors.
 Can be identified by just looking at the wrong output of
the program.

 Runtime Errors:-
 A runtime error occurs when the program directs the
computer to perform an illegal operation such as
dividing a number by zero.
 When runtime error occur, the computer will stop
executing the program and may display a diagnostic
message that helps in locating the error.

Implement the Program
(deployment)
 Once the program has been tested thoroughly, it must
be installed or put into operation at the site where it
will be used.

Maintain & Update the Program
 Program maintenance is ongoing process of upgrading
the program to accommodate new hardware and
software.
 Regular maintenance is essential to the continued
usefulness of a program.

Document the program
 Documentation is a detailed description of a program’s
algorithm, design, coding method, testing and proper
usage.
 A comprehensive documentation consists of the following:
 A description of what the program is supposed to do.
 A description of the problem solution (the algorithm).
 A description of the program design including any aids used
(flowcharts, algorithms etc.).
 A description of the program’s testing process, including test data
used and result obtained.
 A description of all correctness modification and updates made to
the program.
 A user manual (user guide).

Thank You

Programming fundamentals 2

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