Introductions to Design Logic.pptx IT level

1
Designing
ICT Department
Rift Valley University
Programming Logic

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By: Gadisa A.
Designing Program Logic
INTRODUCTION OF COMPUTER PROGRAMMING
Computer Program – Is a list of instructions that the
computer machine follows to properly accept input,
correctly process them and present the results in the
most understandable way.
Computer Programming – is considered to be an art and
at the same time a science. It is an art because there is
no standard way to interpret a problem and solve it
using a standard form of programming procedures and
styles. It is fast becoming a science because standard
programming practice is starting to be adopted.
Programs fall into two major classes:
• Application Programs – application program is one
that carries out some function directly for a user, such
as word processing or game-playing.
• Operating Systems – operating system is a program
that manages the computer and the various resources
and devices connected to it, such as RAM (random
access memory), hard drives, monitors, keyboards,
printers, and modems, so that they may be used by
other programs.
Three types of applications programs translate
from source code to object code:
• Compilers – Computer software that translates
(compiles) source code written in a high-level
language (e.g., C++) into a set of machine-
language instructions that can be understood by
a digital computer's CPU.
• Interpreters – Is a computer program that directly
executes instructions written in a programming or
scripting language, without requiring them
previously to have been compiled into a
machine language program.
• Assemblers – Is a program that converts
assembly language into machine code. It takes
the basic commands and operations from
assembly code and converts them into binary
code that can be recognized by a specific type
of processor. Assemblers are similar to compilers
in that they produce executable code

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By: Gadisa A.
INTRODUCTION OF COMPUTER PROGRAMMING
Computer is composed of:
1. CPU (Central Processing Unit) – this is where all mathematical and
logical forms of processing are done on data.
2. Memory – before a computer can do any productive work such as
programming, it has to remember things such as data it needs to
produce information.
3. Input and Output Device – data have to come into the computer by
first entering them through input devices. Ex. Keyboard. After the
computer executes a program to process data and produce
information, this information remains in the memory.
Part of the program has to show these results to the outside world.
Output devices such as monitor screen and printers are used to display
the results to the user.
4.Software – computers today come bundled with some software
already installed in them. Operating System – performs for the
programmer many tasks that used to be very difficult to program
Two forms of Memory
• Internal Memory (RAM-Random Access Memory) – stores programs
and data that are executed and processed by the computer.
• Secondary Memory – supplements RAM so those computers are able
to permanently save programs and data that are not yet needed for
execution and processing. Ex. Floppy disk, hard disk & etc.
The following are standard Operating System functions.
• Validating user identification every time the user uses
the computer
• Provides standard functions like editor, compilers and
linkers
• Manages files of the user by providing functions like
Copy, Delete, Append
• Retrieves data out of data files
• Manages memory for the user by determining where in
the memory a program is to be loaded every time it is
called to run
• Makes communication between the CPU, Memory and
input/output devices transparent to the user or the user
are unaware of these things while they are at work.

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By: Gadisa A.
COMPUTER LANGUAGE
Programming Language
• A programming language is a set of rules that provides
a way of telling a computer what operations to
perform.
• A programming language is a set of rules for
communicating an algorithm
• It provides a linguistic framework for describing
computations
• The grammatical rules are called syntax.
• Each programming language has a different set of
syntax rules.
Why are there so many programming languages?
• Programming languages have evolved over time as
better ways have been developed to design them.
o First programming languages were developed in
the 1950s.
o Since then thousands of languages have been
developed.
• Different programming languages are designed for
different types of programs.
Classification of Programming Language
Programming Languages - Generations
• High level languages
o 4th Generation Data query, analysis and reporting
o 3rd Generation Imperative
• Low level languages
o 2nd Generation Assembly
o 1st Generation Machine code

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By: Gadisa A.
COMPUTER PROGRAMMING
High level languages
• Programming languages that are closer to human
language than to machine language. They are
characterized to use common English words as their
instructions. Aside from that, high level languages have
the following characteristics:
• A compiled program is usually not as efficient as when
the program was originally written in machine language
or assembly. Each of these programming languages
was designed to solve particular kinds of problems.
• COBOL – Common Business Oriented Language was
designed to solve business problems like accounting.
• FORTRAN – Formula Translation is a high level language
used for scientific and engineering applications.
• Pascal and C – are general-purpose language. They are high-
level language but they can be embedded with assembly
language code effectively making these languages middle-level
languages. C language is responsible in the implementation of
major software including operating systems, compilers and
software development tools
The Simplest computer programs perform three basic operations:
Get the input from the keyboard.
Process the input data.
Display the results on the screen.
INPUT DATA PROCESS DATA
DISPLAY ALL
RESULT

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By: Gadisa A.
COMPUTER LANGUAGE
Low-Level Language:
• Machine code and Assembly code
High-Level Language:
• A programming language that allows programs to be written
using English keywords and is platform independent
Low-Level Language:
• Advantages
o Achieves a smaller memory footprint (compact).
o Achieves better code optimization and therefore code will
run faster and more efficiently.
o Allows direct manipulation if the registers on the processors,
giving high levels of control.
o Processors in these systems may be slow and have limited
memory so the efficiency of assembly language or
machine code is needed. Also useful real time control
systems where speed is very important.
o Since you are writing at machine level you control the level
of the code created.
o Can be easily modified.
• Disadvantages
o More difficult to understand, maintain and debug than
high level languages.
o More difficult to write without making errors.
o Machine dependent making it difficult to port to a different
instruction set processor Memory addresses and operations
have to be remembered Low Level Languages.

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By: Gadisa A.
COMPUTER LANGUAGE
What are the types of programming languages?
• First Generation Languages
• Second Generation Languages
• Third Generation Languages
• Fourth Generation Languages
• Fifth Generation Languages
First Generation Language
• Machine language
o Operation code – such as addition or subtraction.
o Operands – that identify the data to be processed.
o Machine language is machine dependent as it is the only
language the computer can understand.
o Very efficient code but very difficult to write.
Second Generation Languages
• Assembly languages
o Symbolic operation codes replaced binary operation codes.
o Assembly language programs needed to be “assembled” for
execution by the computer. Each assembly language
instruction is translated into one machine language
instruction.
o Very efficient code and easier to write.
Third Generation Languages
• Closer to English but included simple mathematical notation.
o Programs written in source code which must be translated
into machine language programs called object code.
o The translation of source code to object code is
accomplished by a machine language system program
called a compiler.
• Alternative to compilation is interpretation which is accomplished by
a system program called an interpreter.
• Common third generation languages
o FORTRAN
o COBOL
o C and C++
o Visual Basic
Fourth Generation Languages
• A high level language (4GL) that requires fewer instructions to
accomplish a task than a third generation language.
• Used with databases
o Query languages
o Report generators
o Forms designers
o Application generators

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By: Gadisa A.
COMPUTER LANGUAGE
Fifth Generation Languages
• Declarative languages
• Functional(?): Lisp, Scheme, SML
o Also called applicative
o Everything is a function
• Logic: Prolog
o Based on mathematical logic
o Rule- or Constraint-based
Beyond Fifth Generation Language
• Though no clear definition at present, natural language programs
generally can be interpreted and executed by the computer
with no other action by the user than stating their question.
• Limited capabilities at present.
The principal paradigm
• Imperative Programming (C)
• Object-Oriented Programming (C++)
• Logic/Declarative Programming (Prolog)
• Functional/Applicative Programming (Lisp)
Traditional Programming Language
• FORTRAN
o Formula Translation.
o Developed at IBM in the mid-1950s.
o Designed for scientific and mathematical applications by
scientists and engineers.
• COBOL
o Common Business Oriented Language.
o Developed in 1959. ◦ Designed to be common to many
different computers.
o Typically used for business applications.
• BASIC
o Beginner’s All-purpose Symbolic Instruction Code.
o Developed at Dartmouth College in mid 1960s.
o Developed as a simple language for students to write
programs with which they could interact through terminals.
• C
o Developed by Bell Laboratories in the early 1970s.
o Provides control and efficiency of assembly language while
having third generation language features.
o Often used for system programs. ◦ UNIX is written in C.

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By: Gadisa A.
HIERARCHY OF HIGH LEVEL LANGUAGES
High Level Languages
• High level languages are problem-orientated whereas low level
languages are machine-orientated.
• Problem-orientated means that the commands and the way the
program is structured are based on what the program will have
to do rather than the components of the computer it will be used
with.
• This means that programs of high level languages are portable.
These programs can be written on one computer and then
executed on another.
• There are 2 classified groups of high level languages
o Imperative: tells the computer how to do things
o Declarative: focuses on what we want to get from the
computer
High Level
Programming
Languages
Imperative
Object
Oriented
Procedural
Declarative
Logic
Database
Query
Functional

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By: Gadisa A.
ALGORITHM
What is an algorithm?
• A set of steps to accomplish a task
• An algorithm is a sequence of unambiguous instruction
• An algorithm is a well-defined procedure that allows a
computer to solved a problem.
• An algorithm is a self-contained step-by-step set of
operation to be performed to solve a specific problem.
How to write an algorithm?
• Keep in mind that algorithm is a step-by-step process.
• Depending upon programming language, include syntax
where necessary.
• Include variables and their usage.
• If they are any loops, try to give sub number lists.
• Try to give go back to step number if loop or condition fails.
• Use jump statement to jump from one statement to
another.
• Try to avoid unwanted raw data in algorithm.
• Use break and stop to terminate the process.
Characteristics of an Algorithm
• Unambiguous − Algorithm should be clear and
unambiguous. Each of its steps (or phases), and their
inputs/outputs should be clear and must lead to only
one meaning.
• Input − An algorithm should have 0 or more well-defined
inputs.
• Output − An algorithm should have 1 or more well-
defined outputs, and should match the desired output.
• Finiteness − Algorithms must terminate after a finite
number of steps.
• Feasibility − Should be feasible with the available
resources.
• Independent − An algorithm should have step-by-step
directions, which should be independent of any
programming code.
Two forms of Algorithm:
• Pseudocode
• Flowchart

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By: Gadisa A.
ALGORITHM: PSEUDOCODE
Pseudocode
Pseudocode essentially is English with some defined rules of
structure and some keywords that make it appear a bit like
program code. Some guidelines for writing pseudocode are as
follows.
Pseudocode Guidelines
• The keywords used for pseudocode in this document are:
1. for start and finish
BEGIN MAINPROGRAM, END MAINPROGRAM
2. for initialization
INITIALISATION, END INITIALISATION
3. for subprogram
BEGIN SUBPROGRAM. END SUBPROGRAM
4. for selection
IF. THEN, ELSE, ENDIF
5. for multi-way selection
CASEWHERE. OTHERWISE. ENDCASE
6. for pre-test repetition
WHILE. ENDWHILE
7. for post-test repetition
REPEAT. UNTIL
• Keywords are written in CAPITALS.
• Structural elements come in pairs,
o for every BEGIN there is an END
o for every IF there is an ENDIF. etc.
• Indenting is used to show structure in the algorithm.
• The names of subprograms are underlined.
o This means that when refining the solution to a problem. a
word in an algorithm can be underlined and a subprogram
developed.
This feature enables the use of the 'top-down' development
concept. where details for a particular process need only be
considered within the relevant sub-routine.

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By: Gadisa A.
ALGORITHM: FLOW CHARTS
Flow Charts
• A drawing that uses symbols interconnected with lines to represent the
flow of information
• A process flow diagram that illustrates the successive steps in a process,
procedure, system or model.
• A pictorial representation showing/describing all of the steps of a
process being studied or even used to plan stages of a project.
Purpose of Flow Charts
A Flowchart is used for:
1. Defining and analyzing processes
2. Building a step-by-step picture of the process for analysis, discussion, or
communication purposes
3. Defining, standardizing, or finding areas for improvement in a process
By visualizing the process, a flowchart can quickly help identify bottlenecks
or inefficiencies where the process can be streamlined or improved.
Basic flow charting shapes and symbols
Flowcharts use special shapes to represent different types of actions
or steps in a process and Lines and arrows show the sequence of
the steps, and the relationships among them.
Start/End – The terminator symbol marks the starting or ending point
the system. It usually contains the word "Start" or "End."
Action or Process – A box can represent a single step ("add two
cups of flour), or and entire sub-process ("make bread") within a
larger process.
Decision – A decision or branching point. Lines representing
different decisions emerge from different points of the diamond.

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By: Gadisa A.
Connector – Indicates that the flow continues where a matching
symbol containing the same letter) has been placed.
Flow Line – Lines indicate the sequence of steps and the direction
of flow.
Input/ Output – Represents material or information entering or
leaving the system, such as customer order (input) or a product
Example of Flowchart

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By: Gadisa A.
Common Types of Flowcharts
There are four flowchart types that are particularly versatile. These
four common diagrams are great for describing business,
manufacturing, or administrative processes, seeing how an
organization functions, or how different departments work together.
1. The Process Flowchart
Illustrate How a Process Works or Plan a Project with a Process
Flowchart
A process flowchart or process flow diagram is probably the
most versatile of the four commonly used flowchart types
because it can be applied to virtually anything.
• Map out roles and responsibilities within an organization to
gain clarity.
2. The Workflow Chart
Understand How Data and Documents Flow Within Your
Organization
A workflow chart shows the way a business or process functions.
This type of workflow diagram can be used to:
• Train new employees
• Discover potential problem areas
• Clarify business operations by showing a high-level overview
3. The Swim lane Flowchart
Describe How Separate Departments, Processes or Employees
Interact
The swim lane flowchart comes in handy when you need to show
multiple flows of information side by side.
A swim lane flowchart or diagram is great for documenting a whole
process that interacts with different segments of an organization or
requires collaboration among different teams.
4. The Data Flowchart
See Where Data Flows In and Out of an Information System with a
Data Flow Diagram
A data flowchart or data flow diagram shows the way data is
processed. It comes in handy when you want to design or analyze a
system. Although most often used for software development and
design, it can be used to analyze any type of information flow, like
how information moves through a business.

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By: Gadisa A.
Steps for creating a flowchart are:
1. Familiarize the participants with the flowchart symbols
2. Brainstorm major process tasks. Ask questions such as
"What really happens next in the process? ", "Does a
decision need to be made before the next step? ", or
What approvals are required before moving on to the
next task?"
3. Draw the process flowchart using the symbols on a flip
chart or overhead transparency.
Every process will have a start and an end (shown by
elongated circles). All processes will have tasks and most
will have decision points (shown by a diamond).
CONSTRUCTION/INTERPRETATION tip for a flow chart.
• Define the boundaries of the process clearly.
• Use the simplest symbols possible.
• Make sure every feedback loop has an escape.
• Analyze flow chart of actual process.
• Analyze flow chart of best process.
• Compare both charts, looking for areas where they are
different. Most of the time, the stages where differences
occur is considered to be the problem area or process.
• Take appropriate in-house steps to correct the
differences between the two separate flows.

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By: Gadisa A.
Tips for Effective Flowcharts
1. Label each flowchart with a title identifying the process that it
illustrates. (For example: Entry Process").
2. Clearly indicate the starting and ending points of the process,
using the standard terminator symbols.
3. Keep the direction of flow consistent. Avoid confusion by
keeping your flow lines moving from top to bottom and left to
right.
4. Break the steps down to a consistent level of detail. Don't
include trivial sub-steps of one task while treating another
equivalent task as a whole.
5. Avoid crossing flow lines. In a well-designed chart, flow lines will
not cross each other. By rearranging a chart, you can usually get
rid of crossed lines
6. Make sure there are at least two no outcomes from every
decision diamond.
5. Label your flowchart components. Use active verbs to label
activity steps and questions to label decisions. Clearly label the
form a decision diamond in terms that answer the question.
Flowchart and Pseudocode

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By: Gadisa A.
DATA TYPES
Data Types
• A data type defines a set of values and a set of operation on
those values. A C++ program may need to required different
type of data. Each type required different type of memory.
• It indicates the type of data that can be store in a variable
• There are three basic data type.
o Character
o Integer
o Float
Character data type
• This data type is used to store character values.
• Characters may include letters, digits and punctuation
character. It take one byte in memory i.e. ‘a’ and ‘@’ etc.
• Represented by the “char” data type.
We can declare it as below.
Char a= ‘A’
Char f= ‘B’
Char z= ‘D’ etc
Integer data type:
• A numeric value with no fraction is called integer data. It include
both positive and negative values.
• Represented by “int”
• Int range –32,768 to 32,767
• Some example of integer value are 56 and -12
• Int size is ‘2’ bytes
• Long int size ‘4’ bytes
We can declare it as below.
Int a=20;
Int b=40;
Int c=30;

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By: Gadisa A.
DATA TYPES
Type of Integer data type
Int data type
• To store integer values and takes two byte in memory. i.e.
int num;
Long int data type
• To store large integer value. It has greater range and takes ‘4’
bytes in memory. i.e. long int num;
Float data type:
• A numeric value with fraction is called real data type / float data
type. It include both
• Positive and negative values. i.e. 12.4 and -34.3
• This data type are represented by “float”.
• Float number are declared as
Float a= “40.00”
Float b= “23.04”
Float c= “10.3” etc.
Type of float
• Float data type
o This data type is used to store real values and
o Takes ‘4’ bytes in memory. i.e. Float num;
• Double data type
o It has great range as compared to float and takes ‘8’ byte
in memory. i.e. Double num;

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By: Gadisa A.
DATA TYPES
Variable
• A quantity whose values may change during the execution of the
program is called variable.
• It may be a numeric or non-numeric quantity
• It represented by an identifier called variable name
• A variable represents a memory location in the computer memory.
Data is store into the memory location. The name of memory location
or variable name remains fixed during the execution of the program
but the data store in that location may change from time to time
Variable Declaration
• A variable is case sensitive, that is, uppercase variables are treated
differently
• Variable “SUM” is different from variable “sum”
• Variable “NetPay” is different from variable “NETpay”
Rules for variable Declaration
• Variable may include letter, number and underscore (_)
• The first latter of the variable must be character or underscore.
• Blank spaces special symbols, commas are not used
• A variable can be ‘31’ character long for many compilers
• Key word are not used as variable name.
Variable Declaration
• The process of specifying the name and its data type is called
variable declaration
• All variables that are used in a program are declared using
variable declaration statement.
• When a variable is declared a certain number of bytes in the
memory are allocated to the variable name.
Variable Initialization
• The process of assigning a value to a variable at the time of
declaration is known as variable initialization.
• The equal (=) is used to initialize a variable.
• Variable name is given on the left side and value is given on the
right side of equal sign.

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By: Gadisa A.
Designing Programming Logic
if Statement
‘if’ statements test whether a certain condition has been reached,
such as whether a number has reaches a certain value, and if true,
executes the statements in the brackets.
The code in the brackets is skipped if the statement is false.
The syntax for if statement is:
void loop(){
if(some variable <test condition> value){
Do Something;
}
}
The above condition test compares some variable with a value. If this
condition is satisfied, then the code inside the parenthesis (do
something) is executed.
STRUCTURE: CONTROL STRUCTURE
If…else
The ‘if…else’ statements allow either/or statements to be made.
These statements can be used when more than one courses of
action are possible, as determined by the variable or value being
tested. The syntax for ‘if…else’ implementation is:
void loop(){
if(inputPin == HIGH){
doThing1;
}else{
doThing2;
}
}

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By: Gadisa A.
If…else if ladder
If more than two courses of action are possible, then the
‘if…else if’ ladder is to be used, which allows the choice
and execution of one statement from an infinite number of
possibilities. The syntax is as follows:
void loop(){
if(input Pin <test condition> value1){
doThing1;
}else if(input Pin <test condition> value2)
{
doThing2;
}else if(input Pin <test condition> value3)
{
doThing3;
}else{
doThing4;
}
}
for Statement
The ‘for’ statement is used to repeat a statement of a block
of statements a specified number of times. The arguments for
the ‘for’ loop consists of:
1. Initialization. This initializes a variable with a specified initial
value.
2. Test condition. This condition is tested for every loop and
the ‘for’ statement stops looping when this condition does
not hold true.
3. Increment/decrement expression. This expression operates
on the initialized variable.
The syntax for the ‘for’ loop is as follows:
void loop(){
for(initialization; condition;
increment/decrement expression){
Do Something;
}
}

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By: Gadisa A.
while Loop
The ‘while’ loop will loop continuously and infinitely, until
the expression inside the brackets become false. If the
tested variable of value is not changed, the loop will go on
for infinity.
void loop(){
while(variable <test condition> value){
Do Something;
}
}
do…while Loop
The ‘do…while’ class works in a similar manner to the
‘while’ class, the only difference being, that, in the ‘do…
while’ class the condition is tested at the bottom of the loop,
making sure the loops is carried out at least once.
void loop(){
do{
Do Something;
}while(variable <test condition> value)
}

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By: Gadisa A.
FUNCTIONS: MATH
min(x,y)
Returns the smaller of the two values passed into the
function as arguments.
void loop(){
int x,y;
int smaller Num = min(x,y); //Sets
smaller Num equal //to x or y
depending upon //whichever is smaller
}
max(x,y)
Returns the larger of the two values passed into the
function as arguments.
void loop(){
int x,y;
int larger Num = max(x,y); //Sets
larger Num equal to
//x or y depending upon
//whichever is
larger
}

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By: Gadisa A.
FUNCTIONS: RANDOM NUMBERS
randomSeed(seed)
Sets a value as a starting point before the random() function. The
seed can be any variable, input, constraints or other functions. Must
be used before the random function.
void loop(){
randomSeed(analogRead(3)); //Uses the analog value at
//pin 3 to set a
starting //point for the
random //function
}
random(min,max)
This function helps in generating pseudo-random values for the
given range in the arguments. The function randomSeed(seed)
must be used before using this function.
void loop(){
int value_1;
int value_2;
rendomSeed(analogRead(3));
value_l = random(100); //Sets value_l equal to any
//random number between 0
and //100
value_2 = random(50,100): //Sets value_2 equal to any
//random number
between SO //and 100
}

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By: Gadisa A.
REFERENCE
https://www.arduino.cc/
https://en.wikipedia.org/wiki/Arduino
https://www.slideshare.net/

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