Programming Logic and System Analysis
CHAPTER 10
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Chapter Objectives
• Define the meaning program logic and a computer program.
• Describe the relationship between computer programming logic and computer
programs.
• Explain the process of solving a problem with program logic and a computer
program.
• Describe why program logic is modeled with pseudo code and flow charts
before being transformed into a program.
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Programming Logic
What is programming logic?
 Programming logic is used by programmers to model the
programming language instructions carried out by the
computer when the program is executed. Think of program
logic as instructions you might give someone on how to
make something or perform a task they have never done
before. Program logic structure instructions might provide a
program decision or a loop through a series of repeated
instructions. You might also think of your logic model as a
blue print where you have mapped out the instructions but
have yet to put them in a program as program language
statements. Programming logic is programming language
independent which means logic concepts can be used
across all programming languages.
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Computer Programming
What is computer programming?
 Computer programming is an activity performed by
a computer programmer. It includes a process of
creating logic models which is converted into
program language instructions that are later
executed on a computer. The goal of the program
is to solve a problem or perform a task. A
computer program provides instructions for the
computer. Computer programs are made up of
programming language statements.
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Computer Programming
What is programming language statements?
 Programming language statements are used to
implement program logic by sending instructions
to the operating system via programming language
syntax or statements. Programming language
statements are English like statements that when
executed in the correct sequence can instruct the
computer to perform a series of tasks.
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Logic
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Logic Tools
There are various ways of capturing programming
logic, but for this course we will focus on two
main ways:
Pseudo Code and Flowcharting.
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Pseudo Code

A common way for a computer programmer to model or create a solution
before he or she writes the actual computer statements (code) is to use a
method of documentation called Pseudo Code.

The word “pseudo” loosely means informal and not genuine. While this is a
strange word and definition, we use the words “pseudo code” to describe
computer code that cannot be executed on a computer as written but is an
informal guide to what actual computer code needs to be written.

Pseudo Code is a nonstandard English-like programming language used by
programmers to model logic and instructions. Pseudo code is called a
programming language even through it cannot be excluded by a computer. It
is designed for planning purposes only.
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Pseudo Code

Pseudo code provides us with a way to concentrate on
just logic of the task without being distracted by the
syntax rules of a particular programming language

Pseudo code has long been used for modeling logic
before the logic is implemented as source code
statements in a program. We use pseudo code because
it is an excellent way to just concentrate on
programming logic without being constrained by the
rules of a specific programming language.
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Pseudo Code

The beauty of pseudo code is that since it is a list of
instructions, you can easily document the process steps
with others.

Even persons with no understanding of programming
logic or computer programming, can participate in the
creation of pseudo code.

In a typical business situation, a programmer may work
with an accountant to work out the pseudo code of a
new accounting process that the business wants to
implement into their computer systems.
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Pseudo Code

Main Procedure Monopoly_Game
Hand out each player's initial money.
Decide which player goes first.
Repeat
Call Procedure Monopoly_Move for next player.
Decide if this player must drop out.
Until all players except one have dropped out.
Declare the surviving player to be the winner.
Procedure Monopoly_Move
Begin one's move.
Throw the dice.
Move the number of spaces on the board shown on the dice.
If the token landed on "Go to Jail,"
then go there immediately.
Else if the token landed on "Chance" or "Community Chest,"
then draw a card and follow its instructions.
Else
follow the usual rules for the square (buying property,
paying rent, collecting $200 for passing "Go", etc.).
End one's move.
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Pseudo Code
Begin
input hours
input rate
pay = hours * rate
print pay
End
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Pseudo Code
Advantages of using Pseudo Code

It is easy to use and create with any text editor.

No special symbols are used to represent specific functions.

Very little specific syntax is required.

Statements can generally be translated on a one-for-one basis.

Pseudo coding the problem logic first drastically reduces time
spent coding.
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Pseudo Code
Disadvantages of using Pseudo Code

It’s not visual so understanding complex
programs may be difficult.

There is no accepted standard, so it varies
widely.

Statements cannot be run as computer code.
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Flowcharting

A flow chart is a technique for graphically
representing logic with a set of symbols.

A flowchart consists of a set of ‘flowchart
symbols’ connected by arrows. Each symbol
contains information about what must be done
at that point and the arrow shows the ‘flow of
execution’ of the algorithm or process. The
purpose of using flowcharts is to graphically
present the logical flow of the program in the
system and defining phases of processing or
decision making.
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Flowcharting
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Flowcharting
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Flowcharting

Flowcharts are easy to create. You can create
them using a variety of software. Many word
processors like Microsoft Word include shapes for
flowcharting. Visio is another product for
flowcharting purposes.

The Internet has a wide array of flowcharting
software for you to try.

The software does not have to be complex to be
effective.
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Flowcharting
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Flowcharting
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Flowcharting
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Flowcharting

Which flowchart shape should you use? If you
are new to flowcharting, the large number of
shapes can be intimidating.

The following examples should help in making
your decision. Most charts can be drawn with
the five basic flowchart shapes listed.
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Flowcharting
Terminal or
Terminator Shape
This shape tells you where the flowchart begins and ends. It
shows the entry point of your flowchart and the exit point. To
designate the start of your flowchart, you would fill this shape
with words like Start or Begin. The words you use are up to
you.
To designate the ending point of the chart, this shape is filled
with words like End, Exit, or Return.
Usually a flowchart has one starting point. However, a
flowchart can have as many ending points as needed.
Sometimes you see this shape drawn as an oval as shown
below.
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Flowcharting
Lines with Arrows
You read a flowchart by following the lines with arrows from
shape to shape. The lines with arrows determine the flow
through the chart. Flowcharts are usually drawn from top to
bottom or left to right. Numbering shapes is optional.
Numbering is helpful if you have to refer to a shape in a
discussion. In RFFlow you can turn on numbering by clicking
on Tools and Number Shapes. Numbering does not
determine the flow of control. That is determined by the lines
with arrows.
If two lines cross, you ignore the perpendicular line and
continue following the line to the next shape. If there may be
confusion as to the path, you can insert a bridge or crossover,
which is a little bump on crossed lines. In RFFlow, you can
insert bridges on crossed lines by clicking on Tools, Global
Changes, and Add Crossovers.
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Flowcharting
Rectangle
In most flowcharts, the rectangle is the most common shape.
It is used to show a process, task, action, or operation. It
shows something that has to be done or an action that has to
be taken. The text in the rectangle almost always includes a
verb.
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Flowcharting
Decision
A decision asks a question. The answer to the question
determines which arrow you follow out of the decision shape.
For example, in the shape below, if it is cloudy, you follow
the arrow down near the word Yes. If it is not cloudy, you
follow the arrow to the right near the word No.
The arrows flowing from the decision shape are usually
labeled with Yes, No or True, False. But you can label them
any way you want as long as the meaning is clear. This shape
has one input arrow. It is usually at the top, but can be on any
corner. The decision shape can have two or three exit points.
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Flowcharting
Circle
If you need to connect to another page or another section of
the chart, and can't draw a line, you can use a circle. You draw
the line to the circle and label the circle with a letter. Then
you place a copy of the circle where you want the flow to
continue. This should be avoided, but sometimes is necessary.
Originally the circle was used only to reference another part
of the chart and the off page connector, shown later, was used
to go to another page. However, the circle is now often used
for both.
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Flowcharting
Guidelines for flowcharts

In drawing a proper flowchart, all necessary requirements should be
listed out in logical order.

The flowchart should be clear, neat and easy to follow. There should
not be any room for ambiguity in understanding the flowchart.

The usual direction of the flow of a procedure or system is from left to
right or top to bottom.

Only one flow line should come out from a process symbol.


Only one flow line should enter a decision symbol, but two or three
flow lines, one for each possible answer, should leave the decision
symbol.
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Flowcharting
The benefits of flowcharts are as follows:

Communication: Flowcharts are better way of communicating the logic of a
system to all concerned.

Effective analysis: With the help of flowchart, problem can be analyzed in
more effective way.

Proper documentation: Program flowcharts serve as a good program
documentation, which is needed for various purposes.

Efficient Coding: The flowcharts act as a guide or blueprint during the
systems analysis and program development phase.

Proper Debugging: The flowchart helps in debugging process.
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Flowcharting
The limitations of flowcharts are as follows:

Complex logic: Sometimes, the program logic is quite
complicated. In that case, flowchart becomes complex and
clumsy.

Alterations and Modifications: If alterations are required the
flowchart may require re-drawing completely.

Reproduction: As the flowchart symbols cannot be typed,
reproduction of flowchart becomes a problem unless you
have the correct software.
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Language of Logic
A look at the language of logic
 Programming in any language would not work without logic.
Logic is the glue that holds together the code, and controls
how it is executed. When it comes time to create the actual
programming statements, every programming language has
its own syntax and way of writing statements that the
language will understand.

No matter what computer language you develop your
program in; all modern languages share some common
statements that control logic in the program. The syntax may
be different from language to language but the intent of the
statements are the same.
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Language of Logic
If then else
 Compound if conditions
 Nested ifs
 Logical primitives
 Case statements
 For loop
 Repeat loop
 While loop

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Systems and System Analysis
What is System Analysis?

Systems are created to solve problems. One can think of the systems
approach as an organized way of dealing with a problem. System Analysis
for this book will mainly deal with the software development activities.
What is a System?

A collection of components that work together to fulfill an objective is a
system. There are three major components in every system: input,
processing and output.

In a system the different components are connected with each other and
they are interdependent. Interdependent means the components rely on
each other for success. The objective of the system is to produce some
output as a result of processing the inputs.
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Systems and System Analysis
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Systems and System Analysis
System Development/Software Development Life Cycle

System life cycle is a process of developing and maintaining systems
.

System development life cycle means a combination of various
activities. In other words we can say that various activities put
together are referred to as system development life cycle. In the
System Analysis and Design terminology, the system development life
cycle means software development life cycle.

Confused? Don’t be. A system can be made up of many individual
programs that work together. We will refer to these programs as
software. System analysis is made up of the software that is part of
the system. We can accomplish system analysis as part of the
system/software development life cycle.
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Systems and System Analysis
There are many different ways of defining the software
development life cycle but most life cycle definitions contain a
form of the following:








System study
Feasibility study
System analysis
System design
Coding
Testing
Implementation
Maintenance
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Systems and System Analysis
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Systems and System Analysis
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Systems and System Analysis
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END OF CHAPTER TEN
End of chapter
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