branching aco101: introduction to computer science

Branching

ACO101: Introduction to Computer Science

Flowcharting is a way

• Of modeling a system• It is the design of the system and it is what we

do in the Inception and Elaboration phases of a project.

Flowcharts : Review

• Are:

–A schematic representation of a process–And a visual way to describe an

algorithm

Shapes used in flowcharts

Terminators are oval (sometimes you see circles)

Processes are rectangles; they always do something

Decisions are diamonds and they always have a question

These flowcharts are all Examples of Branching

Flowchart for an if statement

Flowchart for an if/else

Nested branching

Multiple alternatives

• Sometimes you wish you had more than one else.

• That is what the else if and the switch is for.

Switch and else if flowchart

So here is the sample “if statement” from Scratch

PsCode is…..

• We will choose a question for the crab to ask.• The seeker [crabby] will ask that question• If the question number is divisible by 5 then

the fairy will give a positive answer to the crab• Other wise she will give a negative answer to

the crab.•

Open Visio and copy this flowchart

So what does that look like in code?

• First – pick a question number and save it to memory

• Second – create a crab object– Make a call to a method called getOneQuestion

• Third – create a fairy object– Make a call to a method called getOneAnswer

Retrieve the question and write it to the screen using the variable

Is the question number divisible by 5??

Now lets set up the branching