[Chp 1] Overview of Computers and Programming Languages and Basic Elements of C++

Learning Outcomes:

1. Understand and explain computer hardware and software

2. Understand and explain computer programming and programming languages

[1.1] Brief History Overview of Computers

    The history of computers began with early calculating devices like the abacus, followed by mechanical devices such as Pascal’s Pascaline and Leibniz’s calculator, which expanded aritmetic capabilities. In 1800s, Jacquard’s punched cards introduced the idea of storing instructions, a concept crucial to computing. Charles Babbage designed early programmable machines, and Ada Lovelace is recognized as the first computer programmer.

By the late 19th century, Herman Hollerith’s punched-card machines revolutionized data processing and led to the creation of IBM. The mid-20th century saw the first large computers, including the Mark I and ENIAC, followed by von Neumann’s architecture, which shaped modern computer design. Advances such as transistors, intergrated circuits, and microprocessors made computers smaller, faster, and more affordable.

From the 1970s onwards, personal computers emerged with companies like Apple and IBM, leading to widespread public use. Today, computers are powerful, affordable, and integrated into daly life, supportiing technologies like artificial intelligience, mobile computing, GPS, and global communications.

[1.2] Elements of a Computer System

A computer is an electronic device that performs basic commands such as input, output, storage, and arithmetic or logical operations. A computer system consists of hardware and software, with major hardware components including the CPU, main memory (RAM), input/output devices, and secondary storage.

Central Processing Unit [CPU]

• Acts as the computer’s brain: computes calculations and logical operations

• More powerful the CPU = Higher processsing speeds

Random Access Memory/Main Memory [RAM/MM]

• Connected to the CPU and temporarily stores programs and data while being used — contents are lost once computer is turned off

• Memory is oragnized into memory cells which have a unique location called address of the cell. Address cells stroe instructions or data in binary form

(Binary form is a way of representing information using only two digits: 0 and 1.)

Secondary Storage

• Is a permanent data storage, which can transfer data to and from main memory for processing

• Examples: hard disks, flash drives, CD-ROMs

Input/Output Devices

• Input devices: keyboard, mouse, scanner, camara and secondary storage

  • Accepts data and programs for the computer to compute

• Output devices: monitors, printer, secondary storage

  • Displays results after computer completes computation

Software

• Consists of programs written to perform tasks

• Created using programming languages

• Two main types of software:

  • System programs

    • Controls the computer’s overall operation by managing memory, input/output, storage

    • Ex. operation systems like Windows, macOS, etc

  • Application programs

    • Designed for specific tasks

      • Ex. word processing, spreadsheets, games

    • Theey run under the control of the operating system

[1.3] Language of a Computer

Computers are electronic devices that process information using electrical signals. When you type a character (like A or B), the computer stores it as binary data, not letters.

Types of Electrical Signals

• Analog signals

  • Continuous, smoothly varying waves

  • Used to represent sound (e.g. audio tapes)

  • Copies lose quality overtime

• Digital signals

  • represented using 0s and 1s

    • 0 = low voltage

    • 1 = high voltage

  • More reliable and can be copied exactly

  • Used by computers

(Ex. When you make a copy of an audio tape, the sound quality of the copy is not as good as the original tape. On the other hand, when you copy a CD, the copy is the same as the original.)

Machine Language

• Machine language is the language of a computer

• Consists of sequences of 0s and 1s

• These sequences are called:

  • Binary digits (bits)

  • Binary numbers/binary code

Bits and Bytes

• Bit: one binary digit (0 or 1)

• Byte: 8 bits

• Kilobyte (KB): $2^{10}$ bytes = 1024 bytes

• Larger memory units are built from bytes

Character Encoding

• Every letter, number and symbol is stored as a unique binary code

• Computers use encoding schemes to map characters to binary

ASCII (American Standard Code for Information Interchange) Encoding

• Uses 7 bits

• Can represent 128 characters (numbered 0-127)

• Characters are stored based on their position number

Examples:

• A

  • Position 65

Binary: 1000001

• 3

  • Position 51

Binary: 0110011

NOTE: ASCII positions start at 0, not 1. The binary value is the binary form of the character’s position

[1.4] Evolution of Programming Languages

All computers store and process data as binary, but machine languages may differ for each computer; machine language is machine-dependent. Programming was very difficult and error-prone.

Assembly Language

• Developed to make programming easier than machine language

• Uses mnemonics (easy-to-remember words) instead of binary codes

  • Example:

LOAD instead of 100100
MULT instead of 100110
STOR instead of 100010

• Easier to read and write than machine language

Limitations:

• Computers cannot execute assembly language directly

• Must be translated to machine language

Translator:

• Assembler → converts assembly language into machine code

High-Level Languages

• Designed to be closer to human (natural) language

• Easier to read, write, and understand

• Allow programmers tofocus on logic, not machine details

Examples:

• BASIC, FORTRAN, COBAL, C, C++, C#, Java, Python

Compilers

• High level languages cannot be executed directly

• Must be tranlated into machine language

Translator:

• Compiler → converts high-level language programs into machine code

[1.5] Processing C++ Program

Steps to Processing a C++ Program

STEP 1: Editor

• You write the program by following the syntax of a high-level language, using text editor

• The program is called the source code or source program

• Saved with extension .cpp

  • Example: FirstCPPProgram → FirstCPPProgram.cpp

STEP 2: Preprocessor

• Handles preprocessor directives

• Lines beginning with #

Example: #include <iostream>

• Processed by the preprocessor

• Includes necessary code from libraries before compilation

STEP 3: Compiler

• Checks the program for and syntax errors

• If errors exist → program will NOT compile

  • Syntax error = grammar mistakes in the code

• If correct → translate source code into machine language

• Output is called an ‘object program’

STEP 4: Linker

• Combines the object program with library code

• Libraries contain prewritten code (eg. input/output functions)

• Produces an executable program

STEP 5: Loader

• Loads the executable program into RAM

STEP 6: Execution

• The program is run

• Output is displayed on the screen

Integrated Development Environment (IDE)

• An IDE combines

  • Text editor

  • Compiler

  • Linker

  • Program execution tools

• Makes programing easier

Examples of IDEs:

• Visual C++ Express

• Visual Studio

• C++ Builder

• Dev-C++

Build/Rebuild

• Compiles and links the program automatically

• Produces executable code

[1.6] Programming with the Problem Analysis-Coding-Execution Cycle

Three Main Programming Steps

1. Analyze the problem and design an algorithm

2. Implement the algorithm in a programming language

3. Maintain and modify the program as requirements change

STEP 1: Problem Analysis (IMPORTANT)

1. Throughly understad the problem

• What is the problem asking?

• What must the program accomplish?

2. Understand the Requirements

Requirements may include:

• Does the program:

  • Interact with the user?

  • Manipulate data?

  • Produce output?

• What does the input look like?

• What should the output look like?

• How should results be formatted?

If data is involved:

• Know what the data is

• Know how it is represented

• Look at sample data

3. Break Complex Problems into Subproblems

• Analyze each subproblem seperately

• Determine requirements for each part

STEP 2: Algorithm Design

• An algorithm is a step-to-step solution

• Written in plain language of pseudocode

• Should be clear, logical and correct

Verifying correctness:

• Test with sample data

• Perform mathematical checks if needed

STEP 3: Coding

• Convert the algorithm into C++ code

• Enter code using text editor

• Ensure the program follows C++ syntax rules