C++ Programming Language
Lecture 2

Problem Analysis and
Solution Representation
The Hashemite University
Computer Engineering
Department
(Adapted from the textbook slides)


Outline
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Program development cycle.
Algorithms development and
representation.
Examples.

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Program Development
Cycle
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Program development cycle steps:
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Problem definition.
Problem analysis (understanding).
Algorithm development:
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Ways for algorithm representation:
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Human language
Pseudocode.
Flowcharts (also called UML activity diagram).

Coding.
Execution and testing.
Maintenance.

Recall that such cycle and all the techniques

presented in this lecture are the same for any
programming language you want to use not only
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for C++.


Problem Definition




To understand the problem is half
the solution.
Describe it by precise, up to the
point statements that will make
both analyzing and solving the
problem easier and clearer.

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Problem Analysis
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
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Determine the inputs, outputs, and
the required operations.
Explore all possible solutions.
Pick the easiest, in terms of
implementation cost (space, time)
one.

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Algorithm Development
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Algorithm is a procedure that determines the:
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Actions to be executed.
Order in which these actions are to be executed (which
is called program control and in industry it is called
work flow).


So, it is a plan for solving the given problem.
You must validate the developed algorithm, i.e.
make sure that it solves the correct problem.
You must verify the developed algorithm, i.e.
make sure that it produces correct results.
You must check the feasibility (in terms of the
needed resources, ease of implementation, ease
of understanding and debugging, its expected
execution time, etc.) of the developed algorithm.
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Algorithm Representation
– Human Language
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Use your own language to
represent the steps of the
developed algorithm.
Example: adding two integers:
1. Prompt the user to enter two numbers.
2. Add them and store the result.
3. Display the sum to the user on the screen.
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Algorithm Representation
– Pseudocode
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Artificial, informal language used to develop
algorithms.
Kind of structured English for describing
algorithms.
Middle approach between human language
and C++ code.
It is convenient and user friendly.
Not actually executed on computers
Allows us to “think out” a program before
writing the code for it
Usually easy to convert into a corresponding

C++ program
Consists only of executable statements, i.e.
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no definitions orThedeclarations.


Pseudocode Notations I
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Input:
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Output:
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Input from keyboard: Get.
Input from file or memory location: Read.
Output to printer: Print.
Output to file: Write.
Output to screen: Display, Prompt (usually
followed by Get).


Values assignment:
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Initial values: Initialize, Set.
Results of computation: =, .
Keeping variables for later use: Save, Store.
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Pseudocode Notations II
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Arithmetic computation:
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Control structures:
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Either use exact operators (+, *, /, -) or
equivalent words of them (add, multiply, divide,

subtract).
Computations: either use Compute or represent
the actual operation mathematically. E.g.
Compute average or avg = sum/count.
Use the actual words as it is: If, If – then – Else,
While, do – While, For – to --, ...

Relational operators:
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Write them as words: greater then, less than or
equal, etc.
Or you can use their symbols: >, <=, etc.
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Pseudocode Examples


Adding two numbers:
1.
2.
3.
4.
5.
6.

7.

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Prompt user for number1
Get number1
Prompt user for number2
Get number2
Add number1 and number2
Set sum to the result
Display sum

Other examples (on board):
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Deciding the grade (A-F) of a student.
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Algorithm Representation
– Flowcharts
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Represent the algorithms or computer programs

execution steps graphically.
The American National Standards Institute (ANSI)
published a standard for flowcharts that includes a
definition of their symbols (see next slide).
Pseudocode is preferred over flowcharts since:
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More readable.
Can be converted into C++ code easier.

Flow charts are very similar to the UML (Unified
Modeling Language) activity diagram with some
differences in the used symbols.
UML is an industry standard for modeling software
systems.
We will study flowcharts not activity diagrams in
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this course.


Flowcharts Symbols


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Flowchart Examples
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Numbers
addition
example.

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Decision flow chart

Chapter 2 - VB.NET by
Schneider

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Looping flow chart

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Example III
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Write a program that reads three
numbers from a file. If the
multiplication of these numbers is
greater than or equal their sum then
print “Winner” on the screen”,
otherwise print “Loser” on the screen.
Solution:


On board.
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Class Average Algorithm
Problem: Calculate and report the gradepoint average for a class
 Discussion: The average grade equals
the sum of all grades divided by the
number of students
Output: Average grade
Input: Student grades
Processing: Find the sum of the grades;
count the number of students; calculate
average

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Flowchart

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Pseudocode
Program: Determine the average grade of a class
Initialize Counter and Sum to 0
Do While there are more grades
Get the next Grade
Add the Grade to the Sum
Add 1 to the Counter
Loop
Compute Average = Sum/Counter
Display Average
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Coding
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Writing the source code of your solution
that is to convert the developed algorithm

into code statements of the used language,
i.e. C++.
Some useful tips:
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Make sure of using correct syntax.
Use meaningful identifiers to make your code
more readable.
Add suitable documentation and comments.
Make your code modular or structured as
possible.
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Execution and Testing
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Compilation and debugging.
Types of errors:
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Syntax errors (Compile time errors):
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Errors caught by compiler

Logical errors (Runtime errors):
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Errors which have their effect at execution time
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Non-fatal logic errors
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program runs, but has incorrect output
Fatal logic errors
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program exits prematurely

Tracing to verify your program with
different sets of inputs.
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Maintenance

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Not always applicable in education,
i.e. highly required in real world jobs.
Update your code based on:
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Discovered and reported bugs.
Customer feedback to make your
application more efficient and flexible.
Upgrade the code.
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Additional Notes


This lecture covers the following
material from the textbook:


Fourth edition:



Chapter 2: Sections 2.1 - 2.3

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