INTRODUCTION TO PROGRAMMING Lesson Note

Learning Objectives

By the end of the lesson, students should be able to:

Programming is the process of designing and writing instructions that tell a computer how to perform a particular task or solve a problem.

A computer does not normally understand ordinary human language directly. Therefore, programmers use programming languages to write instructions that can be translated into a form the computer can execute.

For example, a programmer may write a program that instructs a computer to:

*Calculate students’ scores.

*Display a message.

*Store students’ records.

*Perform mathematical calculations.

*Process examination results.

*Control a machine or device.

*Create a website or mobile application.

Simple Programming Process

Problem → Algorithm → Program Code → Translation → Execution → Output

A program is a set of instructions written to make a computer perform a specific task.

For example, a calculator application is a program designed to perform calculations.

A program may be very simple, such as one that adds two numbers, or very complex, such as software used by banks, hospitals or large organizations.

A programming language is a formal language used by programmers to communicate instructions to a computer.

Programming languages provide rules and symbols for writing computer programs.

Examples of Programming Languages

Some common programming languages include:

*Python

*Java

*JavaScript

*C

*C++

*C#

*PHP

*Visual Basic

*Swift

*Kotlin

*Ruby

Different programming languages are designed for different purposes, although many can be used for several types of applications.

Programming languages can be classified in several ways. One common classification is based on their level of abstraction.

Low-level languages are programming languages that are close to the machine’s hardware and instruction set.

They include:

Machine language consists of instructions represented in binary digits (0s and 1s) that the computer’s processor can execute directly.

Example:

10110000 01100001

Machine language is difficult for humans to read and write.

Advantages

Disadvantages

Assembly language uses symbolic instructions instead of writing everything directly as binary.

Examples of assembly instructions include:

MOV, ADD, SUB, JMP

An assembler translates assembly language into machine code.

High-level languages are designed to be easier for humans to read, understand and write.

Examples include:

*Python

*Java

*C++

*C#

*JavaScript

*PHP

*Visual Basic

For example, a high-level language can contain an instruction such as:

PRINT “Hello”

This is easier for humans to understand than a sequence of binary instructions.

Advantages of High-Level Languages

Low-Level Language  High-Level Language

Close to computer hardware  Closer to human language

More difficult to learn  Easier to learn

Machine language and assembly are examples Python, Java and C++ are examples

Requires detailed knowledge of hardware Requires less hardware knowledge

Generally less portable  Generally more portable

Can provide fine hardware control  Provides higher-level abstractions

Computers need machine instructions to execute programs. Therefore, many programs written in high-level or assembly languages must be translated.

The major translators are:

A compiler translates a complete program written in a high-level language into machine code or another lower-level form before execution.

Examples of languages commonly associated with compiled implementations include C and C++.

An interpreter translates and executes program instructions during program execution, often step by step.

Python and JavaScript can be used with interpreter-based execution environments.

An assembler translates assembly language into machine code.

Simple Diagram

Source Code → Translator → Machine/Executable Code → Computer Execution

Source Code

Source code is the original program written by a programmer using a programming language.

Example:

Number = 10

Print(number)

Object Code

Object code is the translated machine-oriented code produced from source code by a compiler or assembler.

Difference

Source Code Object Code

Written by the programmer Produced by a translator

Human-readable to varying degrees More directly usable by the computer

Written using a programming language Usually machine-oriented

Can be edited by the programmer Normally not edited like source code

A variable is a named storage location used to hold a value that may change while a program is running.

Example:

Age = 16

Here, age is a variable containing the value 16.

The value could later change.

A constant is a value that is intended to remain unchanged during a program’s operation.

For example, a program may use a constant to represent the value of π.

Data refers to raw facts or values that a program processes.

Examples include:

*Names

*Numbers

*Dates

*Examination scores

*Addresses

Data Types

A data type specifies the kind of value that a variable can hold.

Common data types include:

Whole numbers without a decimal part.

Examples:

10, 25, 100

Numbers containing decimal values.

Examples:

3.14, 12.5, 7.25

A single character.

Examples:

A, B, 7

A sequence of characters.

Examples:

“John”

“Computer Science”

A value representing one of two logical states, commonly:

True

False

Operators are symbols used to perform operations on data.

Arithmetic Operators

Operator Meaning

+ Addition

* Multiplication

/ Division

% Remainder/Modulo

Example:

10 + 5 = 15

Comparison Operators

They are used to compare values.

Examples include:

Equal to (==)

Not equal to (!=)

Greater than (>)

Less than (<)

Greater than or equal to (>=)

Less than or equal to (<=)

Logical Operators

Common logical operators include:

AND

OR

NOT

Most computer programs involve three basic activities:

Input → Processing → Output

Input

Data supplied to a program.

Example: entering two examination scores.

Processing

The computer performs operations on the data.

Example: calculating the average score.

Output

The result produced by the program.

Example: displaying the student’s average score.

Control structures determine the order in which instructions are executed.

The three basic structures are:

Instructions are executed one after another in the order in which they appear.

Example:

Enter number

Add 10 to number

Display result

Selection allows a program to make a decision based on a condition.

Example:

IF score >= 50

Display “Pass”

ELSE

Display “Fail”

Iteration allows a set of instructions to be repeated.

Examples include:

For loops

While loops

Example:

Repeat 5 times

Display “Hello”

Developing a program involves several stages.

Clearly identify the problem that needs to be solved.

Study the problem and determine the required inputs, processes and outputs.

Develop a step-by-step procedure for solving the problem.

Translate the algorithm into a programming language.

Run the program to determine whether it works correctly.

Identify and correct errors found during testing.

Prepare explanations and records about how the program works.

Modify or improve the program when necessary after it has been deployed.

Program Development Cycle

Problem → Analysis → Algorithm → Coding → Testing → Debugging → Documentation → Maintenance

Errors can prevent a program from producing the expected result.

A syntax error occurs when the rules of a programming language are not followed.

For example, incorrect spelling or punctuation in a programming statement may produce a syntax error.

A logical error occurs when the program runs but produces an incorrect result because the instructions are logically wrong.

A runtime error occurs while a program is running.

For example, attempting an operation that the program cannot perform may cause a runtime error.

Programming is important because it enables people to create and control digital systems.

It is used in:

A good computer program should be:

*Correct

*Reliable

*Efficient

*Easy to understand

*Easy to maintain

*Secure

*Well documented

*User-friendly

Although the terms are sometimes used interchangeably:

Programming is the broader process of solving a problem, designing a solution, writing code, testing, debugging and maintaining the program.

Coding mainly refers to writing the instructions in a programming language.

Therefore, coding is an important part of programming.

SUMMARY

Programming is the process of creating instructions that enable computers to perform tasks and solve problems. A program is a set of instructions, while a programming language provides the rules and symbols used to write those instructions.

Programming languages can be broadly classified into low-level and high-level languages. Machine language and assembly language are low-level languages, while Python, Java, C++, JavaScript and other similar languages are high-level languages.

Important programming concepts include variables, constants, data types, operators, input, processing, output and control structures. Program development involves problem definition, analysis, algorithm design, coding, testing, debugging, documentation and maintenance.