MAN2200 - Week1

Introduction to Programming, Flow Charts and Pseudocode

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Introduction to Programming Concepts

• Core Concepts: Logic, algorithms, and error handling.

• Flowcharts:

  • Visual representation of a sequence in processes.

  • Aid in planning program flow before coding.

• Pseudocode:

  • Simplifies complex logic into plain language; aids in error reduction.

• Types of Programming Errors:

  • Syntax Errors: Issues from incorrect grammar within the code.

  • Runtime Errors: Problems occurring during program execution.

  • Logic Errors: Mistakes in the program logic resulting in incorrect outcomes.

Understanding Flowcharts

• Flowchart Definition:

  • is a visual representation of a process or algorithm that uses symbols to indicate the flow of steps, decisions, and outcomes in a sequential order.

• Common Flowchart Symbols:

  

• Flowchart Example

  • The flowchart below illustrates the process behind adding five numbers:

    

• Key points to remember about flowchart

  • The rectangle represents any step in the process of a flowchart.

  • A decision point (the diamond) allows for a branching path where the flow continues based on the decision (e.g., if the answer is "yes," one action is taken, and if "no," a different action is taken).

  • A loop is a sequence of instructions that is continually repeated until a certain condition is reached.

  • Repetition or loops in flowcharts are indicated by arrows looping back to a previous decision point (diamond), which controls whether the process repeat

  • The oval or ellipse shape is used to denote the start and end points of a flowchart.

Programming Errors Overview

• Main Types of Errors: Syntax errors, runtime errors, logic errors.

  

• Importance of Understanding Errors: Aids in debugging and ensuring intended program function.

Syntax Errors

• Definition: Violations of the rules of a given programming language.

• Result: Program fails to compile or interpret correctly.

• Examples:

  • Missing required punctuation or using incorrect keywords.

  • Forgetting to close a parenthesis or quotation marks.

  • In languages like C or Java, semicolons are required, and missing one causes a syntax error.

  • In Python, indentation is part of the syntax, and incorrect indentation leads to a syntax error.

  • Most programming languages require variables to be declared before use and failing to do so causes a syntax error.

Runtime Errors

• Definition: Errors occurring during program execution, potentially crashing the program.

• Result: Program crashes or stops unexpectedly.

• Common Examples:

  • Input mismatch (e.g., letter instead of a number).

  • Dividing by zero.

  • Running out of memory.

  • Memory leaks or infinite loops causing program failures.

  • Type-safe languages handle type mismatch with syntax errors instead.

Logic Errors

• Definition: Errors in the algorithm or logic, where the program runs but produces incorrect results.

• Result: Harder to detect since the program runs but behaves incorrectly

• Common Examples:

  • Incorrect operations (e.g., dividing instead of multiplying).

  • Wrong formulas or variables yielding incorrect results.

  • Infinite loops originating from logical mistakes.

Pseudocode: Writing Logical Steps

• Definition: High-level, informal description of a program focusing on logic without strict syntax.

• Benefits:

  • Allows concentration on program logic rather than syntax details.

  • Offers easy readability akin to natural language.

Pseudocode Example

• Example Logic:

  • IF spaceship sprite touches asteroid THEN

    • show explosion sprite

    • play explosion sound

    • subtract a life

  • END IF

  • IF lives = 0 THEN

    • stop game

    • show game over screen

  • ELSE

    • restart game

  • END IF

Algorithms: Solving Problems Step by Step

• Definition: Step-by-step instructions designed to solve specific problems.

• Importance: Forms the basis of programs and logical processes.

• Examples: Making coffee as an analogy for structured problem-solving steps.

• Key Step: Clearly define the problem and objectives when designing an algorithm.

Programming Languages

• Definition: Set of instructions for performing tasks via computer.

• Variations:

  • Computer Language: Includes coding languages with various purposes.

  • Style Sheet Language: e.g., CSS for document presentation.

  • Markup Language: e.g., HTML for document structuring.

Programming Language Types

• Programming Paradigm: Different approaches for programming, including:

  • Procedural Languages: Sequence-focused instruction.

  • Object-Oriented Languages: Encapsulate data and methods.

  • Functional Languages: Composed of function applications.

  • Low-Level Languages: Closer to machine instructions.

  • High-Level Languages: Closer to natural language; user-friendly.

Popular Programming Languages

• Bash: Shell scripting for task automation in Unix/Linux.

• C: Low-level system programming language.

• C#: High-level, human-readable syntax language.

• C/C++: Compiled languages for execution.

• Assembly and Machine Code: Low-level representations of instructions.

• Python: High-level, widely used for data analysis and machine learning due to readability and libraries (e.g., NumPy, TensorFlow).

• Haskell: Purely functional programming.

• Java: Main language for Android development; also uses Kotlin.

• Swift: Primary for iOS applications, designed to replace Objective-C.

• JavaScript: Adds interactivity to web pages, essential for front-end development.

• PHP: Server-side scripting for dynamic web content.

• R: Used in statistics and data science for powerful data analysis.

• SQL: Language for database management and querying.