UNIT 1

INTRODUCTORY TO PROGRAMMING

1ec201/unit 1/introductory to programming

OBJECTIVES

General Objective :To Understand the Programming Concept and terminology, stage involved in Problem Solving and Programming development.

 Specific Objectives : At the end of the unit you will be able to:

  1. Define programming concept and

terminology 2. Explains on the stages involved in

problem solving

3. Use the design tools to solve a given problem

4. Define errors in ptogramming

2

ec201/unit 1/introductory concepts

Introduction To Programming

important characteristics of well-written computer programs. Integrity : This refer to the accuracy of the

calculations since it will be meaningless if calculations are not carried out correctly.

Clarity : This refer to the overall readability of the program, with particular emphasis on its underlying logic. If a program is clearly written, it should be possible for programmer to follow the program logic with ease.

3

ec201/unit 1/introductory concepts

Cont…

Simplicity : The clarity and accuracy of a program are usually enhanced by keeping things as simple as possible, consistent with the overall program objectives.

Efficiency : This is concerned with execution speed and efficient memory utilization.

4

ec201/unit 1/introductory concepts

Cont…

Modularity : Many programs can be broken down into a series of identifiable subtask that enhances accuracy and clarity of a program and facilitates future program alterations.

Generality : Usually we will want a program to be as general as possible, within reasonable limits. A considerable amount of generality can be obtained with very little additional programming effort.

5

ec201/unit 1/introductory concepts

Definition of Programming Terms

ec201/unit 1/introductory concepts

6

ProgrammeA set of instructions that tells the computer what to do.

ProgrammerA person who writes a program so that data may be processed by a computer.

Cont...

ec201/unit 1/introductory concepts

7

Programming languageA programming language is an artificial language designed to express computations that can be performed by a machine, particularly a computer. Programming languages can be used to create programs that control the behavior of a machine, to express algorithms precisely, or as a mode of human communication.

Types of Popular Programming Languages

ec201/unit 1/introductory concepts

8

BASIC BASIC (Beginner's All-purpose Symbolic Instruction Code) is a family of high-level programming languages to provide computer access to non-science students.Example: HELLO WORLD

main( ){ printf("hello, world");}

Cont…

ec201/unit 1/introductory concepts

9

QBasic QBasic (QuickBASIC) is an IDE (integrated development environment) and interpreter for a variant of the BASIC programming language.Example: HELLO WORLD

 PRINT "Hello, World!"

Cont…

ec201/unit 1/introductory concepts

10

Visual Basic Visual Basic (VB) is the third-generation event-driven programming language and integrated development environment (IDE) from Microsoft for its COM programming model.

Example: HELLO WORLD

 

Private Sub Form_Load() ' Execute a simple message box that will say "Hello, World!" MsgBox "Hello, World!"End Sub

Cont…

ec201/unit 1/introductory concepts

11

CC (pronounced /si/ s e e ) is a designed for implementing system software and used for developing portable application software.

Example: HELLO WORLD

 #include <stdio.h> int main(void){ printf("hello, world\n"); return 0;}

Cont…

ec201/unit 1/introductory concepts

12

C++ C++ (pronounced /si plas plas/ s e e p lus p lus ) is a statically typed, free-form, multi-paradigm, compiled, general-purpose programming language. Example: HELLO WORLD#include <iostream>

int main(){ std::cout << "Hello, world!\n";}

Cont…

ec201/unit 1/introductory concepts

13

PascalPascal is an influential imperative and procedural programming languageExample: HELLO WORLD

program HelloWorld(output);begin Writeln('Hello world!')end.

Types of Programming

ec201/unit 1/introductory concepts

14

Structured programmingA technique for organizing and coding computer programs in which a hierarchy of modules is used, each having a single entry and a single exit point, and in which control is passed downward through the structure without unconditional branches to higher levels of the structure. Three types of control flow are used: sequential, test, and iteration.

Cont…

ec201/unit 1/introductory concepts

15

Modular programming

Modular programming is a software design technique that increases the extent to which software is composed of separate, interchangeable components, called modules.

Cont…

ec201/unit 1/introductory concepts

16

Object-Oriented programming

Object-oriented programming (OOP) is a programming paradigm that uses "objects" – data structures consisting of data fields and methods together with their interactions – to design applications and computer programs.

Stage involved in Problem Solving

ec201/unit 1/introductory concepts

17

It consists of several steps which are known as software life cycle, these are:

Defining and Analyzing Problems Planning of Variables Design Tools Program Writing Program Testing and Debugging Program Documentation

Defining and Analyzing Problems

ec201/unit 1/introductory concepts

18

to identify and understand the problems to resolve. The problems must be clearly define, explicit and the requirements in resolving it. Analyzing the problems will determine the input, process and output, as follows:

Input – da ta to be p ro c e s s e dA set of information called data will be entered into the computer from keyboard, floppy disk, hard disk etc. and stored in a portion of the computer memory.

Explaination: cin (console input) for input – normally assigned to the keyboard.

Cont…

ec201/unit 1/introductory concepts

19

ProcessSequence of interdependent and linked procedures which, at every stage, consume one or more resources to convert inputs into outputs. These outputs then serve as inputs for the next stage until a known goal or end result is reached.

Cont…

ec201/unit 1/introductory concepts

20

Output – the d e s ire d re s ultThe processed data which produced certain result is known as the output. The output data will be presented in a sheet of paper through the printer or display on a monitor. Explanation: cout (console output) for output – normally assigned to the screen.

Planning of Variables

ec201/unit 1/introductory concepts

21

Variables are simply references to memory locations. A well plan use of variables will produce an efficient execution of program in terms of speed and memory utilization.

Design Tools

ec201/unit 1/introductory concepts

22

Programmer will design the whole program, starting from getting the data, process the data and produce the desire output.

Flowchart represents algorithm in graphic form comprising of geometrical symbols which is interrelated by line of flow.

FlowchartFlowcharts are a visual outlining tool or geometrical symbols. They can be used to represent an algorithm.

Cont…

ec201/unit 1/introductory concepts

23

SYMBOL NAME MEANING

Flowline Used to connect symbols and indicate the flow of logic

TerminalUsed to represent the beginning (start) or the end (End) of a task

Input/output

Used for input and output operations, such as reading and printing. The data to be read or printed are describe inside

Cont…

ec201/unit 1/introductory concepts

24

SYMBOL NAME MEANING

Processing Used for arithmetic and data-manipulation operations. The instruction are listed inside the symbol

Decision Used for any logic or comparison operations. The path chosen depends on whether the answer to a question is “yes” or “no”

Cont…

ec201/unit 1/introductory concepts

25

SYMBOL NAME MEANING

Connector Used to join different flowline

Offpage connector

Used to indicate that the flow chart continues to a second page

Predefined Process

Used to represent a group of statements that perform one processing task

Cont…

ec201/unit 1/introductory concepts

26

PseudocodePseudocode is another way to develop the logic

of a program. It is merely writing down the steps to

solve the problem in the correct and logical order. The process is similar to doing an outline before you

write a report.

Cont…

ec201/unit 1/introductory concepts

27

Example: A program is required to read three numbers, add them together and print

their total.Solution:

1. Enter the first number2. Enter the second number INPUT3. Calculate processing. ‘ADD (+) command – PROCESS

4. Get the total of numbers result – OUTPUT

Cont…

ec201/unit 1/introductory concepts

28

IPO chart (Input-Process-Output chart)

IPO is an acronym for Input, Processing and Output. Each

letter represents a column in this three column form: First column lists the variables for the Inputs. Second column shows any processing items

(variables created within the code) as well as the pseudocode or flowchart used to solve the problem.

Third column list the variables that are to be output.

Cont…

ec201/unit 1/introductory concepts

29

Example: A program is required to read three numbers, add them together and

print their total.Solution:

INPUT PROCESSING OUTPUTnumber_1number_2number_3

number 1 + number 2 + number 3 =

Total of numbers

Program Writing

ec201/unit 1/introductory concepts

30

In the design of program it should be written assimple as possible. The main objective is to give

a clear, readable programs through an orderly and disciplined approach to programming.

Cont…

ec201/unit 1/introductory concepts

31

CommentsComments are used to insert remarks into the

source code help to explain about what the program

does. In C, comments can be place anywhere in the

programs. It can be used to include the details of the

project and the programmer who wrote or modified the code.

Cont…

ec201/unit 1/introductory concepts

32

There are two types of comment used. They are:

Multi-line CommentThis type of comment is begins with a /* (slash followed by an asterisk) symbol and ended with

a */ (asterisk followed by an slash) symbol.This typ e o f c o m m e nt is g o o d to be us e d whe n c o m m e nts writte n a re lo ng e r tha n 1 line .

Cont…

ec201/unit 1/introductory concepts

33

Example:

/* This is a program that computes the sum of two integer

numbers * /

Cont…

ec201/unit 1/introductory concepts

34

Single line CommentThis type of comment is used with the // (double slash) symbol and it stops at the end of that

particular line.This typ e o f c o m m e nt c a n be us e d whe n the

re m a rk is o nly 1 line in le ng th.

Cont…

ec201/unit 1/introductory concepts

35

Example:

// This is a preprocessor

Cont…

ec201/unit 1/introductory concepts

36

Header FilesHeader files contain information that is required

to run a program. It is a pre written and tested

function that comes together with the compiler and is

available for the use of the programmers.

Example: #include <iostream.h>

Cont…

ec201/unit 1/introductory concepts

37

Functions A function is a block of statements that is part of

a large program.

Function main( ) A C program must have at least the function

main( ) . Every C function, including main( ), must have a

body enclosed in braces { }.

Cont…

ec201/unit 1/introductory concepts

38

Function block { } The function body, also called blo c k can be of

any size. The function always ends with the re turn command.{ - begin block} - end block

Cont…

ec201/unit 1/introductory concepts

39

Example:

main ( )

{

}

Cont…

ec201/unit 1/introductory concepts

40

Format Code ( Backslash Character Constant)The backslash character constant is also known

as the ‘Escape Sequence’.

Cont…

ec201/unit 1/introductory concepts

41

CODE MEANING\b Backspace\f Form Feed (Page

Feed)\n Newline\r Carriage Return\t Horizontal Tab\v Vertical Tab\’ Single Quote (‘)\” Double Quote (“)\\ Backslash (\)\a Alert (beep)\? Question Mark (?)

Cont…

ec201/unit 1/introductory concepts

42

Example:/* This is a program that computes the sum of two integer numbers */#include <iostream.h> // This is a preprocessor

main( ) // include directive

{

int x, y, sum; cout << “\nEnter first number:”; // This is a prompt cin >> x; // Input from console cout<< “\nEnter second number:”; cin>>y; sum = x + y; // Adding x and y cout << “\nSum =” <<sum; // Output to console return 0; // Returning a value to the environment }

Preprocessor directive

Function name

Begin block

Function Body

End Block

comment

Program Testing and Debugging

ec201/unit 1/introductory concepts

43

Once the program has been written it must be compiled and executed. This is accomplished by

an editor and compiler.An editor lets us type a program, makes

changes and save it to a file. The compiler then translates the program into a

form that the computer can read. Once the program has been compiled and

executed the presence of errors will be readily apparent.

Cont…

ec201/unit 1/introductory concepts

44

Syntactic and execution errors usually result in the

generation of error when compiling or executing a

program.

Syntax ErrorThe most common error a programmer makes.

Usually a miss spelled word. A program will not compile

until all syntax errors are corrected.

Cont…

ec201/unit 1/introductory concepts

45

Run-Time ErrorRun-time errors are errors that occur while your program runs. These typically occur when your program attempts an operation that is

impossible to carry out.

Logical ErrorThese errors solely depend on the logical

thinking of the programmer and are easy to detect if we

follow the line of execution and determine why the

program takes that path of execution.

Program Documentation

ec201/unit 1/introductory concepts

46

Program must be documented for future references

and maintenance process. A well documented program will make it easier for the original programmer or other programmer to follow the program logic and design.

Cont…

ec201/unit 1/introductory concepts

47

Program document should consist of:An accurate specification of

requirement.Detail input, output, constraint and

formula for the above problems.Algorithm in the form of flowchart or

pseudocode.Program source complete with

comment.Sample program which had been run

and executed and the tested data. Guideline on how to use the program.