Lecture-1.pptx . this is about the computer program

Computer Programming
Languages
Lecture – 1

Computer Basics
• Computer systems consist of hardware and
software
• A set of instructions for the computer to carry
out is called a program
• All the different kinds of programs used to
give instructions to the computer are
collectively referred to as software

Hardware and Memory
• The CPU, or central processing unit, or processor,
performs the instructions in a program
• Computer’s memory holds data for the computer
to process
– It holds the result of the computer’s intermediate
calculations
– A byte is the quantity of memory
• 1 gigabyte of RAM is approximately 1 billion bytes of
memory

Hardware and Memory
Main memory consists of a long list
of numbered bytes
The number of a byte is called its
address
A byte is the smallest addressable
unit of memory
Data (numbers, letters and string of
characters) is encoded as a series of 0s
and 1s and placed in the computer’s
memory

Programming Languages
• Computer programs(software) are instructions
that tell a computer what to do
• Many programming languages
– All programs are converted into instructions that
computer can execute
• Types of Languages
– Machine Language
– Assembly Language
– High-Level Language
To add Two Numbers:
1101101010011010
add 2, 3, result
result = 2 + 3
Example

Lecture-1.pptx . this is about the computer program

Programming Paradigm
• A programming paradigm is a fundamental style
of computer programming
• Imperative in which the programmer instructs
the machine how to change its state.
Examples: C, C++, Java, PHP, Python, Ruby etc.
• Declarative the programmer states only
what the result should look like, not how to
obtain it. Example SQL, HTML , CSS

• Structured Programming
– Kind of imperative programming
– Control flow is defined by nested loops, conditionals,
and subroutines
– Sequence, Selection and Repetition
x= 5;
y = 11;
z = x + y;
System.out.println(z);
if (x % 2 == 0)
{
System.out.println("The
number is even.");
}
while(x < 100)
{
System.out.println(x);
x = x * x
}

• Object Oriented Programming (OOP)
– Object-oriented programming is about creating objects that
contain both data and methods
– Classes and objects are the two main aspects of object-
oriented programming
• Examples: C++, C#, Java, Python.
Class Object
Fruit Apple, Banana, Mango
Car Volvo, Audi, Toyota
Student Ali, Hamza, Ahmad

public class Car {
String carReg;
int carModel;
String carClass;
public Car(String num) {
carReg = num;
}
public String getReg(){
return carReg;
}
public static void main(String[] args) {
Car Audi = new Car("AX-7865");
System.out.println(Audi.getReg());
}
}
Example

• Functional Programming
– Basic method of computation is the application of
functions to arguments
– Supports and encourages the functional style
– Examples of FP languages
• Lisp, Haskell, Python

Outline
• Program Development Cycle
• Algorithm
• The First Four Steps
13

Programming: Plan First, Then Code
• A good programmer will plan first and write
second
– Breaking down a large programming task into
several smaller tasks

Algorithm
• Set of well-defined logical steps that must be
taken to perform a task
• For example, suppose you have been asked to write a
program to calculate and display the gross pay for an
hourly paid employee.
Here are the steps that you would take:
1. Get the number of hours worked.
2. Get the hourly pay rate.
3. Multiply the number of hours worked by the hourly pay rate.
4. Display the result of the calculation that was performed in Step 3.

Pseudocode
• Pseudocode: fake code
– Informal language that has no syntax rule
– Not meant to be compiled or executed
– Used to create model program
• No need to worry about syntax errors, can focus on program’s
design
• Can be translated directly into actual code in any programming
language

Flowcharts
• Flowchart: diagram that graphically depicts
the steps in a program
– Ovals are terminal symbols
– Parallelograms are input and output symbols
– Rectangles are processing symbols
– Symbols are connected by arrows that represent
the flow of the program

First Four Steps
Step 1: Work an Example Yourself
Step 2: Write Down What You Just Did
Step 3: Generalize Your Steps
Step 4: Test Your Algorithm

Example-1
Write a program to compute x raised to the y power
(x y)
Step 1: Work an Example Yourself
x = 3 and y = 4, getting an answer of 3^4 = 81.

Example-1
Step 2: Write Down What You Just Did

Example-1
1-Replacing this occurrence of 3 with x

Example-1
2-Find repetition

Example-1

Example-1
• Step 4: Test Your Algorithm

Lecture-1.pptx . this is about the computer program

More Related Content

Similar to Lecture-1.pptx . this is about the computer program (20)

Recently uploaded (20)

Lecture-1.pptx . this is about the computer program

Editor's Notes