Programming

1
CHAPTER 1

• Programming
• Problems Solving

2
Objectives

• Define the meaning of programming and program
  correctly
• List step by step process in program development

3
What is computer programming?

• Process to plan the sequence of instructions that
  will be execute by the computer
• Task / events
• Planning
• Scheduling
• Execution
• To handle specific task / events

4
What is computer program?

• Sequence of instructions that highlight the steps
  to execute by the computer
• Use programming language
• Computer should understand the instruction given
  by the programmer

5
What is Problem Solving?

• Process of transforming the description of a
  problem into a solution of that problem by using
  our knowledge of the problem domain and by
  relying on our ability to select and use
  appropriate problem-solving strategies,
  techniques and tools.
• - page 21, Problem Solving Using C, Yuksel Uckan

6
Problem specifics analysis

• Requirement specification eliminated
  ambiguities in the problem statement.
• Analysis identified problem inputs, outputs
  collected information about the inputs.
• Design developed a series of steps with a
  logical order which, when applied, would produce
  the output of the problem
• Implementation Using tools.
• Testing verification check the output to
  verify the correctness of the method.

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Problem solving approach

• Engineering Science Engineering Science
  method.
• Bussiness-oriented systems approach
• Computer programs software development
  method/software life-cycle

8
Software development methods

• Requirement specification
• Analysis
• Design
• ------------------------------
• Implementation
• Testing Verification
• Documentation

Problem solving phase
Implementation phase
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Requirement Specification

• Understanding what the problem is?
• What is needed to solve it?
• What is solution should provide?
• Constraints special conditions.
• Defining problem depends on degree of
  familiarity with the problem domain. What would
  you do if you dont?

10
Analysis

• Inputs to the problem, their form input media
  to be used
• Outputs expected from the solution, their form
  output media to be used
• Any special constraints or conditions
• Formulas or equations to be used

11
Design

• Method of solution what is define by design?
• Also called as algorithm a sequence of a finite
  number of steps arranged in a specific logical
  order, which, when executed, produce the solution
  for a problem.

12
A quick history of algorithm

• Introduce by a Persian mathematician named Abu
  Jafar Mohammed Ibnu Musa Al-Khawarizmi
• Al-khawarizmi
• A set of procedure that explain the way to solve
  a problem

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Why study algorithms?

• Describes the steps needed to perform a
  computation
• Important for writing efficient code
• Code that execute faster which uses less memory
• A finite number of steps for solving a particular
  problem within a certain time frame.
• A finite step by step problem solving technique

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Characteristics of a good algorithm

• Simple, clear concise readable
• Solvable, terminates after a finite number of
  instructions
• Correct, efficient robust
• Accomplishes at least one task or produces at
  least one output

15
Algorithm representation

• Pseudocode
• A semiformal, Englishlike language with a
  limited vocabulary can be used to design
  describe algorithm.
• Flowchart
• A graph consisting of geometrical shapes that are
  connected by flow lines.

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Guidelines to develop the pseudocode

• Each step has not more than 2 action
• Each steps is execute in-order
• The word End is used to show the end of process
• Selection / conditional structure (optional)
• Repetition / loop structure (optional)
• Use arithmetic symbol

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• Variable name can be declare to identify the
  appropriate its data type represent / hold
  value
• Examples of data types Integer, floating-point,
  character, etc.
• Initial value for variable (optional)
• Logical operator (if required)
• lt, lt, gt, gt, !,

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• Word must be clear meaningful
• Use the word Read / Input / Get for data input to
  algorithm
• Use the word Print / Write / Output to mention
  the output from algorithm

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Flowchart

• Flowcharts were formerly used to describe each
  processing path in a program (the main program
  and various subroutines that could be branched
  to)
• Programmers were admonish to always flowchart
  their logic rather than carry it in their heads
• Use of simple geometric symbols to represent the
  beginning or end of a program (an oval), a
  process (a rectangle), a decision (a diamond), or
  an I/O process (a parallelogram). These symbols
  are defined in ANSI x 3.5 and ISO 1028

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Symbols use in flowchart
Begin / End
Activity Flow
21
Related websites

• Further information
• http//users.erofs.com/zenithco/khawaris.html
• Download tools (free)
• http//www.smartdraw.com

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Guidelines to develop the flowchart

• Identify the correct symbol
• according to their function
• Get a correct formula
• Use the appropriate data
• Test your flowchart
• Trace each symbol compare with the expected
  output

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Example

• Problem Add 2 numbers
• Steps
• Begin
• Read number 1
• Read number 2
• Add number 1 number 2
• End

Read number 1
Read number 2
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Selection Structure

• Single selection
• Bi-selection
• Multi-selection

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Single selection

• Test for one condition only
• Choose either true or false
• There are an alternate flow if the condition is
  true
• Syntax
• Step a
• If ltcondition truegt
• Begin
• Step 1
• Step 2
• . . . . . .
• Step n
• End
• Step n 1

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Example
Problem Compare 2 values. If number 1 is
greater than number 2, print message Number 1
Flowchart

• Pseudocode
• Begin
• Read no1
• Read no2
• If (no1 gt no2 )
• 4.1 Print Number 1
• End

Read no1
Read no2
True
If no1 gt no2
Print Number1
False
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Bi-selection

• Choose either true or false
• 2 different alternate flow for both condition
• Syntax

If ltcondition truegt Begin Step 1 . . . . Step
n End If ltcondition falsegt Begin Step 1 . . .
. Step n End
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Example
Problem Compare 2 values. If number 1 is
greater than number 2, print message Number 1
else print message Number 2

• Pseudocode
• Begin
• Read no1
• Read no2
• If (no1 gt no2 )
• 4.1 Print Number 1
• Else
• 5.1 Print Number 2
• End

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Example Flowchart
Read no1
Read no2
If no1 gt no2
True
False
Print Number 1
Print Number 2
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Multi-selection

• There are several alternative flow regarding to
  the satisfied condition

Problem Compare 2 values. If number 1 is greater
then number 2, print message Number 1. If
number 2 is greater than number 1, print message
Number 2, otherwise print message Equal.
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Example Pseudocode

• Begin
• Read no1
• Read no2
• If (no1 gt no2 )
• 4.1 Print Number 1
• Else If (no2 gt no1 )
• 5.1 Print Number 2
• Else
• 6.1 Print Equal
• 7. End

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Example Flowchart
Read no1
Read no2
True
Print Number 1
If no1 gt no2
False
True
Print Number 2
If no2 gt no2
False
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Repetition Structure

• For
• While
• Do-while

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FOR Loop

• 3 components
• Initial value for counter
• Condition to repeat the loop
• Update the counter
• The counter can be increase / decrease
• Condition might be TRUE or FALSE
• Must test the condition first
• Condition result might be TRUE or FALSE
• If the condition is TRUE, alternate flow will be
  execute

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General Syntax

• FOR (counter initial value test counter
  update counter)
• BEGIN
• Statement 1
• Statement 2
• . . .
• Statement n
• END

Test C
FALSE
TRUE
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Example problem

• Print a multiplication table for 1 to 10 by
  number 2

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Solution Pseudocode

• Begin
• Let TOTAL 0
• For (C1 Clt11 increase value C by 1)
• 3.1 Begin
• 3.2 TOTAL TOTAL 2
• 3.3 Print TOTAL
• 3.4 End
• End

Alternate flow
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Solution Flowchart
True
False
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WHILE loop

• Must test the condition first
• Condition result might be TRUE or FALSE
• If the condition is TRUE, alternate flow will be
  execute
• If the condition is FALSE, skip the alternate
  flow
• If the condition is FALSE at the first test,
  alternate flow will not be execute anymore

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General syntax

• WHILE ltcondition TRUEgt
• Begin
• Statement 1
• Statement 2
• . . .
• Statement n
• End

TRUE
Condition
FALSE
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Example problem

• Do the summation for the input number until user
  key-in 999. Print total

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Pseudocode

• Begin
• TOTAL 0
• INPUT 0
• WHILE (INPUT ! 999)
• 2.1 Begin
• 2.2 Read INPUT
• 2.3 TOTAL TOTAL INPUT
• 2.4 End
• Print TOTAL
• End

Alternate flow
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Flowchart
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DO WHILE Loop

• Condition test at the end of loop
• The loop will be repeated if the condition is
  TRUE
• The alternate flow will be executed at least once

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General syntax

• Begin
• Statement 1
• Statement 2
• . . .
• Statement n
• End
• WHILE ltcondition TRUEgt

Condition
TRUE
FALSE
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Pseudocode

• Begin
• TOTAL 0
• 2.1 Begin
• 2.2 Read INPUT
• 2.3 TOTAL TOTAL INPUT
• 2.4 End
• 2.5 WHILE (INPUT ! 999)
• Print TOTAL
• End

Alternate flow
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Flowchart