Flowcharting and Algorithms – Vocabulary

Flowcharting and Algorithms - Comprehensive Notes

• Flowcharting and writing algorithms are foundational steps in program development

• This set of notes covers definitions, activities, symbols, pseudocode, and practical examples from the provided transcript

• Focus areas include: what programs are, how they are developed (problem understanding, planning, coding, compiling, testing, production), algorithm design, pseudocode, flowcharting, variables and operators, and common flowcharting patterns

Programs, Languages, and Programmers

• Program: a set of detailed, step-by-step instructions that directs the computer what to do; a notation for expressing instructions to be carried out by a computer

• Programs are written in a programming language: a set of rules that tells the computer what operations to perform

• Person who creates programs: programmer

Activities involved in Programming

• Understand the problem

• Plan the logic

• Code the program

• Compile the program into machine language

• Test the program

• Put the program into production

Understanding the Problem

• Programmer must understand the problem before writing code

• Goal: satisfy the user’s need

• Descriptions may be vague; user may not know exactly what they want

• A good programmer acts as counsellor and detective to clarify requirements

Plan the Logic

• Plan for the solution of the problem (ALGORITHMS)

• Two common tools for planning: FLOWCHARTS and PSEUDOCODE

• Involves writing steps in English (high level)

• Do not worry about syntax yet; focus on sequence of events from input to output

Code the Program

• There are over 400 programming languages

• Languages have translators: compilers and interpreters

• Examples: Pascal, C, C++, Visual Basic, Cobol, etc.

• The coding phase focuses on correct syntax (commands, punctuation, spelling, etc.)

• Actual construction of the source code

Compile the Program into Machine Language

• Machine language is the only language a machine truly understands; consists of 0s and 1s

• Compiler translates high-level language instructions into machine language

• Compiler catches syntax errors

Test the Program

• Execute and run the program with various test data to anticipate and fix errors before release

• Error types: (1) syntactical or logical errors, (2) compile-time or run-time errors

• Use sample data to verify proper operation

Put the Program into Production

• Organization begins using the program

• Train personnel to use it

• Run with actual data

• Test for user approval

Algorithm

• A sequence of well-understood steps to do something

• A set of instructions for a person to follow to accomplish a task

• A sequence of instructions that tell how to solve a particular problem

• Examples:

  • Directions for going to a place

  • Baking a chocolate cake

  • Computing income tax

  • Searching for a name in a telephone directory

Example: Prepare a Cup of Coffee

• Step 1: Fill kettle with water

• Step 2: Turn on stove

• Step 3: Put kettle on stove

• Step 4: If water is boiling, proceed to step 5; otherwise wait

• Step 5: Turn off stove

• Step 6: Fill mug with boiled water

• Step 7: Put 1 tsp of coffee in mug

• Step 8: With sugar, put 2 tsp of sugar in mug, otherwise proceed to step 9

• Step 9: With milk, pour 1 tbsp of milk in mug, otherwise proceed to step 10

• Step 10: Stir contents of mug

• Step 11: (implied) Enjoy coffee

Characteristics of an Algorithm

• Specify each step exactly: no ambiguity; clear instructions

• Finite number of steps: algorithm must terminate with a stopping point

• Output: algorithm must produce the correct result

Pseudocode and Flowcharts

• Pseudocode: uses everyday language to describe the steps; abbreviated version of actual code

• Looks more like a real program than a flowchart; helps focus on required steps

• Advantage: can describe a program to nontechnical users and guide code writing

• Pseudocode can describe a program in textual form that translates into actual code

• Pseudocode is a textual presentation of a flowchart; close to natural language; control structures impose logic

• May become part of program documentation; could be translated into a program

Example Algorithm: Total the Expense Receipts for the Month

• Step 1: Total the expense receipts for the month

• Step 2: Subtract the amount of the expense receipts from 1000

• Step 3: If the remainder is > 0, return that amount to the company

• Pseudocode (high level):

  • Begin

  • Get the Expenses

  • If Expenses < 1000 then

  • Subtract Expenses from 1000 (expenses-1000 = remainder)

  • Print "You Owe" and Remainder

  • Else

  • Print "You Owe Nothing"

• End

Pseudocode for Determining Pass/Fail by Grade

• Pseudocode: If student's grade is greater than or equal to 60, print "passed"; else print "failed"

• Sample 1: Pseudocode

  • Begin

  • If Grade >= 60 then Print "passed" else Print "failed"

  • End

• Sample 2: Class average of 10 students (pseudocode)

  • Initialize total to 0

  • Initialize grade counter to 1

  • While grade counter <= 10

  • Input the next grade

  • Add grade to total

  • Increment grade counter

  • Set class average to total / 10

  • Print class average

Flowcharting

What is Flowcharting?

• A graphical representation of the logical steps that solve a problem

• Used to understand the logic processing of data

• Visualizes how statements in a program are interrelated

• Time-consuming but beginner-friendly

• Uses symbols and phrases to designate logic of problem solving

• Defines the basic input, process, and output (IPO) function within a program

• A diagram representing the logical sequence in which steps/operations are performed; a blueprint of the program

Types of Flowcharts

• Program Flowcharts: depict the detailed logical flow of a process in a program

• System Flowcharts: show the data flow from source to destination; divided into department or personnel functions; symbols represent documents and operations; highlights excessive information flow, data duplication, and delays

Basic Flowcharting Symbols (with common meanings)

• Terminal block: Start/End (oval/rounded-rectangle shape)

• Preparation/Initialization: Initial data setup or conditions (often shown as a hexagon on some diagrams; examples include SUM=0 or PRODUCT=0)

• Input/Output: Parallelogram (reads data or prints data): e.g., Read A, Print A

• Process/Processing: Rectangle (computations/assignments): e.g., Sum = A + B

• Decision: Diamond (tests a condition; two possible paths: True/False)

• On-page Connector: Small circle to connect flow within the same page

• Off-page Connector: Pentagon (connexion to other pages)

• Initialization symbol: used to denote setup of data or variables

• Flow lines: arrows showing the sequence of steps

System Flowcharting Symbols (data processing view)

• Data, Process, Decision, Document, Start/End, Direct Data, Stored Data, Internal, Manual Input, Storage, Predefined Process, Sequential Access Storage

Basic Flowcharting Examples and Conventions

• Simple flow from input to processing to output

• Input operation (Read, Print) are represented by parallelograms

• Processing (arithmetic/assignment) shown in rectangles

• Flow lines and terminal symbols indicate correct sequence

• Example: Get number → Answer = number * 2 → Print Answer

Example Representation (Begin/End)

• Begin

• Get number

• Answer = number * 2

• Print Answer

• End

• Note: After designing the flowchart, choose the programming language to implement the flowchart code

Variables

• What are variables? Memory locations whose content may vary/change

• The ability of memory variables to change makes computing possible: one memory location can be reused with different values

• Naming: variable names may differ by language (hyphens, underscores, etc.); some languages limit name length

• Rules for naming variables:

  • Must be one word

  • May contain letters, numbers, hyphens, underscores

  • Must not start with a number

  • Must not contain a space

  • Should have meaningful names

• Invalid variable name examples:

  • interest rate (space) → should be one word

  • rate! (special character) → invalid

  • xyxxx (meaningful but non-descriptive) → not ideal

  • #total (starts with a special character) → invalid

Types of Variables

• Numeric Variables: hold numbers; may be integer/whole numbers or floating-point/decimal

• Character/Text/String Variables: hold letters and punctuation; e.g., NAME = "WASHINGTON"

• Logical/Boolean Variables: can be TRUE or FALSE

Arithmetic Operators and Statements

• Addition (+), Subtraction (-), Multiplication (*), Division (/), Modulus (% )

• A typical numeric statement:

  • leftvariable = leftvariable oparator right_operand(s)

  • Examples: ext{Sum} = A + B \

• Example representations: x = x + 1; sum = a + b

Constants

• A constant is a value that never changes during execution

• Constants can be numeric, alphabetic, or other symbols

• Like variables, constants can be named; memory location holds the constant value

• During execution, the constant is referred to by its name; value cannot be changed

Relational Operators

• Compare two values to determine their relationship

• Examples and returns:

  • op1 > op2: true if op1 is greater than op2

  • op1 >= op2: true if op1 is greater than or equal to op2

  • op1 < op2: true if op1 is less than op2

  • op1 <= op2: true if op1 is less than or equal to op2

  • op1 == op2: true if op1 and op2 are equal

  • op1 != op2: true if op1 and op2 are not equal

Logical Operators (Boolean)

• Used to express relationships between conditions

• Operators:

  • cond1 and cond2: true if both conditions are true

  • cond1 or cond2: true if either condition is true

  • not cond: negation of cond

Flowcharting Examples

Example 1: Going to School

• Start

• Get in Car

• Drive to School

• Park Car

• Walk to Class

• Attend Class

• End

• If not going to class: Walk to Car, Get in Car, Drive Home, End

Example 2: Bath Flowchart

• Start

• Fill the bath with water

• Get undressed

• Get into bath

• Wash

• Get out of bath

• Empty the bath water

• Get dressed

• End

Example 3: Enter 2 Numbers, Compute and Display Sum

• Start

• X = 0, Y = 0, Sum = 0

• Enter X

• Enter Y

• Sum = X + Y

• Print Sum

• End

Example 4: Name and Age, Determine Young or Old

• Start

• Name = " ", age = 0

• Enter Name, Age

• If Age > 18? -> Yes: Print YOUNG or OLD accordingly

• End

Practice: Flowchart and Algorithms for Common Tasks

• Example: Draw a flowchart to accept and display a number; algorithm:

  • Step 1: Read in the value of N

  • Step 2: Print the value of N

  • Start → Read N → Print N → End

• Example: Flowchart to compute and display the sum and product of two numbers; algorithm:

  • Step 1: Initialize Sum and Product to 0

  • Step 2: Read A and B

  • Step 3: Sum = A + B; Product = A * B

  • Step 4: Print Sum and Product

  • Start → Read A,B → Print Sum, Product → End

• Example: Flowchart to convert Fahrenheit to Celsius; formula and algorithm:

  • Formula: C = rac{5}{9}igl(F - 32igr)$</p></li><li><p>Algorithm: Step 1: Celsius = 0; Step 2: Read Fahrenheit; Step 3: Compute Celsius; Step 4: Print Celsius</p></li></ul></li><li><p>Example: Compare two numbers A and B and print higher value with remark "Higher"</p><ul><li><p>Algorithm: Step 1: Read A and B; Step 2: If A > B, print A and "Higher"; else print B and "Higher"</p></li></ul></li></ul><h5 id="bdaeddc7-63b4-48c5-9e99-43e864fe4be1" data-toc-id="bdaeddc7-63b4-48c5-9e99-43e864fe4be1" collapsed="false" seolevelmigrated="true">More Examples (Quiz and Student Data Handling)</h5><ul><li><p>Example: Input grade of a student and determine pass/fail</p><ul><li><p>If Grade >= 60 → Passed; else Failed</p></li><li><p>Print Name, Grade, and Remarks</p></li></ul></li><li><p>Example: Enter scores for a number of quizzes and accumulate total</p><ul><li><p>Initialize counter and total; loop until counter reaches the number of quizzes; input score; add to total; increment counter; end when complete</p></li></ul></li></ul><h4 id="98e2d983-1585-49eb-b564-376b36c664d7" data-toc-id="98e2d983-1585-49eb-b564-376b36c664d7" collapsed="false" seolevelmigrated="true">Switch-CASE and Structured Programming</h4><h5 id="ea3580f2-cb37-4467-b6ce-8ee75534efef" data-toc-id="ea3580f2-cb37-4467-b6ce-8ee75534efef" collapsed="false" seolevelmigrated="true">The Switch-CASE Structure</h5><ul><li><p>A control structure that selects among multiple discrete cases</p></li><li><p>Example image shows a decision path for class and corresponding fees, demonstrating how cases map to outcomes</p></li><li><p>Rationale: simplifies multi-branch decisions</p></li></ul><h5 id="0cf28e00-dafa-49be-ba4d-cb64e7cb480a" data-toc-id="0cf28e00-dafa-49be-ba4d-cb64e7cb480a" collapsed="false" seolevelmigrated="true">Reasons for Structured Programming</h5><ul><li><p>Clarity: structured logic scales better as programs grow</p></li><li><p>Professionalism: expected to use structured designs</p></li><li><p>Efficiency: allows building more efficient programs across languages</p></li><li><p>Modularity: divide into reusable routines that can be assembled</p></li></ul><h4 id="e7016b6a-1f41-44e0-9c49-a3da8e356bc0" data-toc-id="e7016b6a-1f41-44e0-9c49-a3da8e356bc0" collapsed="false" seolevelmigrated="true">Practical Flowcharting Tasks and Algorithms</h4><ul><li><p>Draw a flowchart that accepts and displays a number; equivalent algorithm:</p><ul><li><p>Step 1: Read N</p></li><li><p>Step 2: Print N</p></li><li><p>Start → Read N → Print N → End</p></li></ul></li><li><p>Draw a flowchart that computes and displays sum and product of two numbers; algorithm:</p><ul><li><p>Step 1: Initialize Sum = 0, Product = 0</p></li><li><p>Step 2: Read A, B</p></li><li><p>Step 3: Sum = A + B; Product = A × B</p></li><li><p>Step 4: Print Sum and Product</p></li><li><p>Start → Read A,B → Print Sum, Product → End</p></li></ul></li><li><p>Flowchart to convert Fahrenheit to Celsius (Celsius formula above) and corresponding algorithm</p></li><li><p>Flowchart to input A and B, compare and print which is higher with remark</p></li><li><p>Flowchart to input student name and grade, determine Passed/Failed and print name, grade, and remark</p></li><li><p>Flowchart to input scores for a number of quizzes and accumulate scores</p></li></ul><h4 id="8d2648f7-abb3-47a5-99fb-9b1f98f0e55e" data-toc-id="8d2648f7-abb3-47a5-99fb-9b1f98f0e55e" collapsed="false" seolevelmigrated="true">Summary of Key Concepts and Formulas</h4><ul><li><p>Program vs language vs programmer</p></li><li><p>Algorithm as a sequence of unambiguous steps with finite termination and an output</p></li><li><p>Pseudocode as a bridge between natural language and actual code</p></li><li><p>Flowcharts as graphical representations of IPO (Input-Process-Output) logic</p></li><li><p>Basic flowcharting symbols and their meanings: Terminal, Initialization, Input/Output, Process, Decision, On-page Connector, Off-page Connector</p></li><li><p>System flowcharting adds data flow, documents, and storage elements</p></li><li><p>Variables: memory locations with names; rules for naming; types (Numeric, Text/String, Boolean)</p></li><li><p>Arithmetic operators:</p><ul><li><p>$+,\, -, \, \, ackslash?, etc.$(common: +, -, *, /,$C = rac{5}{9}igl(F - 32igr)$</p></li></ul></li><li><p>Sum and Product of two numbers:</p><ul><li><p>$ ext{Sum} = A + B$</p></li><li><p>$ ext{Product} = A imes B$$

• Example logical condition checks:

  • If value X greater than Y: X > Y

  • If two conditions must both be true: cond1 \land cond2

  • If either condition is true: cond1 \lor cond2

  • Negation: \neg cond

Note: The above notes reproduce the major concepts, definitions, examples, and the common patterns and structures from the transcript. They are organized to function as a comprehensive study guide that mirrors the content presented in the slides, including both high-level ideas and specific step-by-step examples.