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Understanding Flowcharts in Computer Programming: A Comprehensive Overview

This document outlines the essential elements of flowcharts as a programming tool. It discusses their evolution, symbols, and how they represent program behavior. Flowcharts allow programmers to visualize logic flow, focusing on algorithms rather than syntax. It includes methods for representing control structures like if-else and loops, as well as practical applications for creating flowcharts in assignments and labs. The document also highlights the importance of flowcharts in structured design and algorithm development, helping to make complex problems manageable.

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Understanding Flowcharts in Computer Programming: A Comprehensive Overview

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  1. EEE 243BApplied Computer Programming 11 - Flowcharts §Appendix C Sylvain P. Leblanc

  2. Review • What are the three ways to use the name of a function in a program? • Are identifiers required for the parameters in a function prototype? • Can you use a void function in an assignment expression? • Why/Why not • What information does the type of a variable give us? Prof S.P. Leblanc

  3. Outline • Representing Program Behaviour • Flowchart Evolution and Motivation • Flowchart Symbols • Auxiliary • Primary • Flow Control Flowcharts • if-else • switch • for • while • do…while • Flowcharts and EEE243 Prof S.P. Leblanc

  4. 1. Representing Program Behaviour • In the lectures 08 and 09, we have seen flow of control structures: functions, if-else, else-if, switch, while, for and do-while • There are several methods to represent the logic behind the use of these constructs • Pseudo code – English like statements • Flowcharts – Graphical • Chapin diagrams – Graphical Prof S.P. Leblanc

  5. Flowcharts vs. Structure Charts • The Structure Charts that we discussed with functions are also a graphical method, but they are different: • Structure Charts describe the hierarchical organization • Flow Charts describe the behaviour • In Flowcharts, each of the flow control constructs can be graphically represented • Regardless if you use OOAD or structured programming, flowcharts can help you visualize the logic flow of a program Prof S.P. Leblanc

  6. 2. Flowchart Evolution • Flowcharts used to be the main design tool for symbolic languages to represent the logic flow of a program • Flowcharts fell out of grace when new analysis and design techniques emerged • Flowcharts were seen as not scalable for large scale designs • Before diagrammatic tools, flowcharts were drawn by hand using stencils Prof S.P. Leblanc

  7. 2. Flowchart Evolution • The production of these charts was tedious, and for large monolithic programs, they were difficult to manage • For large programs it used to be common to see “wall flowcharts” • So why do we still use them? • Our programs are no longer huge monolithic lines of assembler code • We decompose our problems into manageable parts (functions) Prof S.P. Leblanc

  8. 2. Flowcharts Motivation • Flowcharts are now used to describe the inside of functions; not the entire program • A flowchart shows an algorithm– a way to solve a problem • The flowchart frees the programmer from the syntax and details of the programming language and allows him to concentrate on the details of the problem to be solved • A pictorial representation of our programs allows us to think more clearly • There are several software tools that you can use to draw flowcharts. • PowerPoint was used for all these charts • Visio also has this capability Prof S.P. Leblanc

  9. 3a. Flowcharts – Auxiliary Symbols • We will not cover all the symbols here, we covered the main symbols that you will need to produce algorithms • Terminal symbol – shows start and end of algorithms • Flow lines – Shows the order of actions • Connector – Shows connecting points in algorithm: • When we reach the end of a page or column, • When we want to show something that does not fit in the flow Start n Prof S.P. Leblanc

  10. 3b. Flowcharts – Primary Symbols • Assignment Statements • I/O Statements • Call to a function in another module • Compound Statement sum = a + b mult = a * b READ (a) x  abs() frommath.h Prof S.P. Leblanc

  11. 4a Flowcharts – if-else T F a > 10 Something Something else Prof S.P. Leblanc

  12. 4a Flowcharts – switch a ? m n o Something n Something m Something 0 Prof S.P. Leblanc

  13. 4. Flowcharts - for Initial condition Condition Update F T Something Prof S.P. Leblanc

  14. 4. Flowcharts – while Condition F T Something Prof S.P. Leblanc

  15. 4. Flowcharts – do…while Something T Condition F Prof S.P. Leblanc

  16. 5. Flowcharts in EEE243 • Note that you will be required to create a flowchart to hand in for one of your labs • I recommend flowcharting to capture solution you develop when faced with a problem • Step 4 in the structured design procedure we covered in lecture 04 • Flowcharts are at the same conceptual level a C code • But flowcharts make it easier to see the algorithm .. It represents a different abstraction • Most student’s generate their flow chart afterwards instead of using it as a design tool • That’s a mistake! • Practice with flow charting, and complex problems will become easier to solve. Prof S.P. Leblanc

  17. Quiz Time • Why are flow charts useful? Prof S.P. Leblanc

  18. Next Lecture • Arrays and Command Line Arguments Prof S.P. Leblanc

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