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In this tutorial, we explore the fundamental role of flowcharts in program design, drawing an analogy between analysts and architects. Clear communication of designs is crucial for developers. We cover various flowchart symbols, including decision points, inputs/outputs, and processes. Learn how to represent sequences, selections, and iterations effectively. Through practical examples, such as reading numbers and conditional logic, you'll gain insights into algorithm design fundamentals. Harness the power of flowcharts to enhance your programming skills and communicate your designs with clarity.
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Tutorial #7Flowcharts (reprise) Program Design
Introduction • We mentioned it already, that if we thing of an analyst as being analogous to an architect, and a developer as being analogous to a builder, then the most important thing we can do as analysts is to explain our designs to the developers in a simple and clear way. • How do architects do this?
Symbols Decision Terminal Input/Output Operation Connector Module Process
Flowcharts • So we start the program as: START
Flowcharts • Our program will finish with the following: END
Flowcharts • When we write programs, we assume that the computer executes the program starting at the beginning and working its way to the end. • This is a basic assumption of all algorithm design.
Flowcharts • When we write programs, we assume that the computer executes the program starting at the beginning and working its way to the end. • This is a basic assumption of all algorithm design. • We call this SEQUENCE.
START Statement1 Statement2 END
Flowcharts • What if we want to make a choice, for example, do we want to add sugar or not to the tea?
Flowcharts • What if we want to make a choice, for example, do we want to add sugar or not to the tea? • We call this SELECTION.
START Is Sugar required? Add Sugar Don’t Add Sugar No Yes END
Flowcharts • What if we need to tell the computer to keep doing something until some condition occurs?
Flowcharts • What if we need to tell the computer to keep doing something until some condition occurs? • Let’s say we wish to indicate that the you need to keep filling the kettle with water until it is full.
Flowcharts • What if we need to tell the computer to keep doing something until some condition occurs? • Let’s say we wish to indicate that the you need to keep filling the kettle with water until it is full. • We need a loop, or ITERATION.
START Keep Filling Kettle Kettle is not full? No Yes END
Flowcharts • So let’s say we want to express the following algorithm: • Read in a number and print it out.
START Read in A
START Read in A Print A
START Read in A Print A END
Flowcharts • So let’s say we want to express the following algorithm: • Read in a number and print it out double the number.
START Read in A
START Read in A Print A*2
START Read in A Print A*2 END
START Read in A
START Read in A B = A*2
START B = A * 2 can be read as “B gets the value of A multiplied by 2” Read in A B = A*2
START Read in A B = A*2 Print B
START Read in A B = A*2 Print B END
Flowcharts • So let’s say we want to express the following algorithm: • Read in a number, check if it is odd or even.
START Read in A
START Read in A Does A/2 give a remainder?
START Read in A Does A/2 give a remainder? Print “It’s Odd” Yes
START Read in A Does A/2 give a remainder? Print “It’s Odd” Print “It’s Even” No Yes
START Read in A Does A/2 give a remainder? Print “It’s Odd” Print “It’s Even” No Yes END
Flowcharts • So let’s say we want to express the following algorithm to print out the bigger of two numbers: • Read in two numbers, call them A and B. Is A is bigger than B, print out A, otherwise print out B.
START Read in A and B
START Read in A and B A>B?
