lecture-2- intro to programing

7/27/2019 Lecture-2- Intro to Programing

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Introduction to Computer Programming- CSC141

Muhammad Usman Yaseen

Muhammad Usman [email protected]

Introduction to ComputerProgramming- CSC141


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Recommended Books:

Text Book / Essential Reading:

Introduction to computers, Peter Norton, 4thEdition

A book on C by Kelly

Reference Books / Literature:

Computer Today, Donald H Sanders, 3rd Edition

Computers, H.L Capron 6th Edition Let us C by Yashvant Kanethar

Turbo c/c++ programming by Robert Lafore




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Computer programming

Humans are intelligent and computers are

dumb.

Humans can think on their own, computers

cant.

Humans know what to do, computers dont.

Computers need to know what to do.

They rely on humans.

Humans control computers

Very simply, telling the computer what to

do is called computer programming!Muhammad Usman [email protected] to ComputerProgramming- CSC141


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Computer program

A computer needs instructions to perform

a task.

It just cant decide on its own not at all!

The instructions have to be

Detailed

Step by step

Exact Accurate

Complete




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computer program

The set of step by step instructions followingwhich, a computer can perform the requiredtask, is known as a computer program.

These instructions Are written by a human being, called a computer

programmer to Control the computer.

Make use of the computers tremendous power to get the

job done.

Computer programming can also be simplydefined as writing computer programs.




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I/O

Recall that

Every task to be done, problem to be solved

requires some input.

The input need to be processed in a certain

manner.

The processing generates some kind of

results that solve the problem. So input, processing, output is the

simplest way to solve any problem.




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I/O

It all starts with the output.

Getting the output is the objective.

Feeding the input is a requirement.

Processing the input to get to the output is

what needs to be done.

This is where you solve the problem!




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Some examples

Problem: a glass full of orange juice is

needed.

Input: a couple of oranges.

Processing:

1. Cut the oranges

2. Squeeze the oranges

3. Catch the juice flowing out of the oranges

into a glass.

Output: a glass full of orange juice drink

it! Muhammad Usman [email protected] to ComputerProgramming- CSC141


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some examples

Problem: shirt needs to be pressed.

Input: a wrinkled shirt.

Processing:1. Heat the iron.

2. Adjust the shirt on a flat surface.

3. Press the shirt with the hot iron until thewrinkles go away.

Output: a wrinkle-free pressed shirt.




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Computers I/O

Computers also rely on input, processing

and output.

You need to get something done from the

computer, you need the output.

The computer needs relevant input to get

to the output.

It gets the input, processes it, and

generates the output.




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computers I/O

Computer




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Computer program

You want the computer to do something,

you want the output.

You have the required input to get the

output from.

You need the computer to process the

input and give the output, but

The computer doesnt know what to do

remember?




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computer program

So you need to tell the computer how to

process the input to get the output.

You will tell it through detailed step by step

instructions.

Step by step instructions are a computer

program.




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computer program

So you instruct the computer, step by step,

telling it what to do, how to do to

produce the output you need through the

input you feed!

Thus, a computer program instructs the

computer to

Accept the input through input devices.

Process the input and generate the output.

Give the output back through output devices.




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computer program

Everything that happens inside a computer

is under its processors control.

To make the computer do something, you

need to instruct the processor.

So a computer program instructs the

computers processor to perform the task.

A computer program has instructions

written in it, which a computer can

understand.

Com uter ro ram = com uter software.Muhammad Usman Yaseen

[email protected] to ComputerProgramming- CSC141


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computer program

Everything that a computer does isgoverned by a computer program.

There are different programs/software that

make the computer perform differentactivities.

Examples of programs

Microsoft windows Microsoft word

Adobe Photoshop

etcMuhammad Usman Yaseen

[email protected] to ComputerProgramming- CSC141


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Programming language

You communicate with humans in a

language they understand.

You need to communicate with a computer

in a language it understands.

The language a computer understands is

called Machine Language.

Its extremely complicated.

So complicated that its not understandable for

humans.




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programming language

To communicate with somebody who

doesnt understand your language, you

need to translate your language into his

language.

To communicate with a computer, you

need to

Write instructions in a language that you

understand.

Translate those instructions into machine

language that the computer understands.Muhammad Usman [email protected] to ComputerProgramming- CSC141


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programming language

A language which you use to writecomputer programs is called programminglanguage.

The language you write programs in has to beone that you can understand.

Programming languages that humans canunderstand are known as high level languages.

The computer only understands machinelanguage.

You need to write programs in high levellanguages and convert/translate them into

machine language.Muhammad Usman [email protected] to ComputerProgramming- CSC141


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Coding

A computer program you write in a high

level language is also referred to as

Source Code.

Programming is also referred to as

Coding.

A person who writes computer programs is

sometimes referred to as a Coder.

The word Programmer is more appropriate

and more common.




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Translator

Microsoft Word is a computer program

which helps you compose text documents.

Microsoft Paint is another program which

helps you draw images.

Similarly, there are programs you use to

translate programs you write in high level

languages into corresponding machine

language.




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translator

A program that translates the entire source

code into its machine language equivalent

in one go is called a Compiler.

Compiler is said to compile the source code.

A program that translates the source code

into its machine language instruction by

instruction is called an Interpreter. Interpreter translates one instruction at a time.

Muhammad Usman Yaseenusman [email protected]


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