Computer Programming Basics

Computer Programming

• Computer: An electronic device that accepts data from the user.
• Data: Unstructured facts and figures; lacks information about patterns, context, etc.
• Information: Structured data.
• Hardware: Mechanical devices that make up a computer. Interconnected electronic devices that control input, output, and the computer's information.
• Computer Hardware: Components that work together.
• Software: A set of instructions, also called a program.

Two Types of Software

• System Software: Operates directly on computer hardware. Used to run applications (e.g., Linux, Unix, Windows).
• Application Software: Used to perform tasks (e.g., Word, Excel, PowerPoint, Oracle).

Program or Software

• A list of instructions that the computer must follow to process data into information.
• To solve a problem, use logic to develop detailed instructions.

Five Steps of Programming

• Define the problem.
• Design the solution/program.
• Code the program.
• Test the program.
• Document the program.

Top-Down Approach

• The overall task is broken down into generalized subtasks.

Modularization

• Long programs are split into smaller programs.

Pseudocode

• A plain language description of steps in an algorithm or system.

Program Coding

• Translates program logic (using pseudocode or flowcharts) into a programming language.

Syntax

• Grammatical structure of a programming language.

Semantics

• Meaning and interpretation of a programming language.

Program Testing

• Desk checking, debugging, and running real data to ensure a program works correctly.

Desk Checking

• Manually reading through a program's code to find errors.

Debugging

• Detecting, locating, and removing program errors.

Syntax Errors

• Typos or incorrect formatting.

Logical Errors

• Mistakes in the source code, leading to wrong outputs or program crashes.

Documenting the Program

• Written descriptions of the purpose and usage of a program.

User Documentation

• Manual helping users understand how to use the program.

Operator Documentation

• Manual giving the computer operator instructions on program errors messages and actions to take.

Program Documentation

• Documentation is used to train new programmers on maintaining existing computer systems.

Program Logic Formulation

• Step-by-step development of a solution to a problem.

Flowchart

• Visual representation of a program or algorithm using boxes with different shapes connected by lines.

System Flowchart

• Flowchart for a complete targeted system.

Program Flowchart

• Flowchart that illustrates the detailed process of a program.

Structured Flowchart

• Orderly, understandable, and clear solution using three basic methods of control.

Sequential Structure

• Strict sequence of instructions.

Selection Structure

• The program chooses between multiple actions.

Repetition Structure

• Steps that are repeated.

Algorithm

• A set or series of instructions.

Algorithm Development

• Creating algorithms using flowcharts/pseudocode, and ensuring they are understandable and clear.

High-Level Languages

• Programming languages used by computers.

Symbolic Names (Identifiers)

• Names used in programs to represent quantities.

Input/Output Operations

• Read or enter (input) or display, print, and write (output)

Basic Combined Programming Language (BCPL)

• Programming language developed in 1967.

B Language

• Programming language developed in 1970, used for the first UNIX system.

C Language

• Programming language developed in 1972, designed for the UNIX operating system.

Turbo C

• Version of C used on microcomputers developed by Borland.

Source Code

• Text that users can read.

Interpreter

• Reads source code.

Compiler

• Converts source code to object code.

Object Code

• Code executed by the computer.

Compile Time

• Events during the compilation process.

Run Time

• Events during program execution.

Syntax Errors (Run Time)

• Errors detected during program execution.

Logical Errors (Run Time)

• Errors detected when the output is incorrect.

Runtime Errors

• Errors that arise during the program's execution, often when a program asks for an integer or number input but receives text.

Library

• Collection of pre-written codes.

Turbo C Environment

• Complete Software environment for creating, testing, and running Turbo C programs.

Turbo C Components

• Editor: Used to produce source code.
• Extended C Language: Makes Turbo C compatible with updated standards.
• Compiler: Converts source code into machine code.
• Debugger: Helps test and diagnose errors.
• Run-time Environment: System enables program execution.
• User Interface (UI): A user-friendly interface for the Turbo C environment.

Identifiers (C Language)

• Names used to refer to objects in the program.

Rules for Naming Identifiers

• Names must start with a letter or underscore and can include subsequent letters, numbers, or underscores. No spaces or hyphens. First 63 characters are significant, and the case matters.

Data Types (C Language)

• Simple Data Types (int/integer): Whole numbers (optional + or -), followed by digits; cannot contain commas. Used in conditional statements and loops.
• Short int: Byte size 2. Range -32768 to +32767.
• Long int: Byte size 4. Range -2,147,483,648 to +2,147,483,647.
• Float: Signed numbers with decimal points and/or digits after the decimal. Occupies 4 bytes
• Double: Special float storing more significant digits. Occupies 8 bytes. Range 1.7E-308 to 1.7E+308.
• Char: Single letter, digit, punctuation mark, or control symbol within single quotes. Can be assigned an integer between -128 and +127.
• Unsigned Char: - Can be assigned values from 0 to 255.
• Void: Declares a function that returns no value.

Variables (C Language)

• Identifiers that hold values.
• Declaration: Give a variable a name and reserves memory.
• Initialization: Assign values to variables. Can be done in declaration or later.
• Global Variables: Declared outside functions; accessible throughout the program. Initialized to zero unless otherwise specified.
• Local Variables: Declared inside functions; only accessible within that function. Initialized to zero unless otherwise specified.

Constants (C Language)

• Fixed values that cannot be changed during program execution.
• Types of constants: character, integer, floating-point, and string.

Modifiers (C Language)

• Const: Variables declared as const cannot be changed during program execution.
• #Define, Const: Symbols used for declaring constants.
• Type Modifiers: Used to adjust the meaning of a basic data type (e.g., short, long).

Assignment Statements

• Used to assign values to variables using the '=' operator.

Operators

• Symbols used for mathematical, relational, and logical operations.

Conditional Statements

• If, else, switch: Used to control program flow based on conditions.

Single Selection Statements

• If/if-else statements

Multiple Selection Constructs

• Switch statements: Executes code blocks based on different conditions.

Unconditional Transfer Statements

• Break Statement: Terminates a loop or a switch case block.
• Continue Statement: Skips the rest of the current loop iteration while the loop continues to run .