COMP 14: switch, Developing ProgramsAnnouncementsReviewReview (cont.)TodayswitchSlide 7Slide 8Slide 9Slide 10switch examplecomments on switchDeveloping programsSlide 14Example: assignment P2Establishing requirementsCreating a designSlide 18Exciting new term!1) ask for names2) ask for day of birth3) determine winner4) print out resultNow turn this into codeYour turn!PB&J requirementsNow break down the taskSo now we have 1 level...A well-known algorithmAssignment P3Opening existing projectsHomeworkCOMP 14: switch, Developing ProgramsJune 2, 2000Nick VallidisAnnouncementsP3 due Tuesday, June 6ReviewHow does the do loop work?How does the for loop work?dostatement;while (condition);for (initialization; condition; increment)statement;Review (cont.)What are the 4 ways to decrement a variable?What's the difference between ++i and i++?Todaythe switch statementSteps to take in developing a programswitchThe switch statement format:switch (expression){case exp1:statement1;break;case exp2:statement2;break;default:statement;}switchThe switch statement format:switch (expression){case exp1:statement1;break;case exp2:statement2;break;default:statement;}JavareservedwordsswitchThe switch statement format:switch (expression){case exp1:statement1;break;case exp2:statement2;break;default:statement;}The expression is evaluated and control jumps to the case whose value matches. If there is no matching case, then control goes to defaultswitchThe switch statement format:switch (expression){case exp1:statement1;break;case exp2:statement2;break;default:statement;}The statements are executed starting from the corresponding case until it gets to a break. At a break, control jumps to the end of the switchswitchThe switch statement format:switch (expression){case exp1:statement1;case exp2:statement2;break;default:statement;}But the break statements are optional, so you could just run on to the next case if you leave it outswitch example// i is a character the user typed inswitch(i){case ‘a’:case ‘A’:System.out.println("You entered 0");case ‘Z’:System.out.println("You entered 1");default:System.out.println("You entered " +"something other than 0 or 1");}comments on switchonly works with integral types (any primitive type except boolean or the floating point types)This is basically an equality testDeveloping programsThe book describes for basic stepsestablishing the requirementscreating a designimplementing the codetesting the implementationDeveloping programsFor the small code fragments we've done in class, we've gone straight for the implementationFor the rest of your assignments, it will really help you to go through this processExample: assignment P2We'll use assignment P2Establishing requirementsHere are the requirements:read in two namesgreet the usersread in the day of the month that each of the people was bornreport winner as person born earlier in monthif it's a tie, report that it's a tieAnything else?Creating a designWe'll start by breaking it down into manageable steps:1) ask for players' names1.5) greet users2) ask for players' days of birth3) determine winner (or that it's a tie)4) print out resultCreating a designThen we can either break things down again if they're still big tasks, or get down to writing specifics.This is simple enough that we'll go to specifics next.Exciting new term!pseudocode - a mixture of programming statements and English Example:if class is overeveryone can leaveelseeveryone stays1) ask for namesprompt for first nameread in first nameprompt for second nameread in second name2) ask for day of birth ask (first name) for day of birthread in day of birthask (second name) for day of birthread in day of birth3) determine winnerif (days of birth are equal)it's a tieelse{if (person 1's day < person 2's day)person 1 was born firstelseperson 2 was born first}if (days of birth are equal)print it's a tieelse{if (person 1's day < person 2's day)print person 1 was born firstelseprint person 2 was born first}4) print out resultTurns out that it's easier to combine 3&4Now turn this into codeThe pseudocode should be written such that turning it into code is trivial.Your turn!Try this with the PB&J exampleLet's talk about the requirements together first...PB&J requirementswhat you have:robot w/ 2 arms, jar of PB, jar of J, 2 slices of bread, 1 knifewhat you have to do:make PB&J sandwichrobot can only take simple instructionsNow break down the taskAim for a maximum of about 7 steps at any one levelSo now we have 1 level...Now break down each of these tasks into their steps.Repeat this until you get down to steps you know how to program!A well-known algorithmMaybe you've seen this before?LatherRinseRepeatWhat's wrong with this as an algorithm?Assignment P3Here's the order you should probably try to do things:Get the framework going - announcing the game, asking name, etc.make the higher-lower game work once. (don't worry about checking for valid input)add the "do you want to play again?" loopadd checking for valid inputdo the extra creditOpening existing projectsSome people have had trouble with getting their programs to run after they quit Visual J++2 of the ways to do this:(if it's your machine) go to the File menu and right above exit will be the names of recent projectsclick on my computer and keep going through folders till you get to the right one and double-click on <project name>.slnHomeworkread 4.1-4.2 (and 3.3, 3.5 if you missed that)P3 is due Tuesday (start