Program One. Program Two. import acm.program.*;

Transcription

1 Scope Tracing Below are a few short programs. Your job is to determine what the output of each program will be without running the programs. It is extremely difficult to figure out what these programs are going to do purely by looking at them. Instead, try drawing lots of pictures. We recommend that you do the following: Whenever you call a method, draw a box that will hold the variables for that method. Have a dedicated space where you'll put the values of all the variables in each method. Have a dedicated space for output produced by println. Remember you'll need to keep track both of what gets printed and the order in which it gets printed. Remember that variables in one method aren't visible inside of other methods. Make sure you have a way of keeping track of which method each variable is stored in. Remember that variables are passed by value. To make it easier to talk about the programs, we've added in line numbers.

2 Program One public class FindingJava extends ConsoleProgram { 2: int dory = 1; 3: int marlin = 2; 5: nemo(dory, marlin); 7: println("dory = " + dory); 8: println("marlin = " + marlin); 9: 11: private void nemo(int jenny, int charlie) { 12: jenny += charlie; 13: println("jenny = " + jenny); 1 println("charlie = " + charlie); 15: Program Two public class JavaTopia extends ConsoleProgram { 2: int judy = 1; 3: int nick = 2; 5: bogo(judy); 7: println("judy = " + judy); 8: println("nick = " + nick); 9: 11: private void bogo(int dawn) { 12: int bonnie = dawn; 13: dawn *= 5; 1 println("dawn = " + dawn); 15: println(" bonnie = " + bonnie); 1

3 Program Three public class TheJungleJava extends ConsoleProgram { 2: int mowgli = 1; 3: baloo(mowgli); 5: println("mowgli = " + mowgli); 7: 8: 9: private void baloo(int mowgli) { mowgli = 137; 11: println("mowgli = " + mowgli); 12: Program Four public class BigJavaSix extends ConsoleProgram { 2: int hiro = 1; 3: int tadashi = 2; 5: wasabi(tadashi, hiro); 7: println("hiro = " + hiro); 8: println("tadashi = " + tadashi); 9: 11: private void wasabi(int hiro, int tadashi) { 12: println("hiro = " + hiro); 13: println("tadashi = " + tadashi); 1

4 Program Five public class MonstersJavaVersity extends ConsoleProgram { 2: int mike = 1; 3: int sulley = 2; 5: randy(sulley, mike); 7: println("mike = " + mike); 8: println("sulley = " + sulley); 9: 11: private void randy(int mike, int squishy) { 12: int sulley = 10 * mike + squishy; 13: println("mike = " + mike); 1 println("sulley = " + sulley); 15: println("squishy = " + squishy); 1 Program Six public class AliceInJavaLand extends ConsoleProgram { 2: int alice = 2; 3: println("the secret number is " + madhatter(alice)); 5: 7: private int madhatter(int cheshirecat) { 8: return cheshirecat + 10 * cheshirecat; 9:

5 Program Seven public class JavaOfTheCarribean extends ConsoleProgram { 2: int jacksparrow = 3; 3: jacksparrow = elizabethswann(jacksparrow); 5: println("jacksparrow = " + jacksparrow); 7: 8: private int elizabethswann(int willturner) { 9: return willturner * willturner; Program Eight public class JavaStory extends ConsoleProgram { 2: int woody = 4; 3: int buzz = 5; woody = andy(woody, buzz); 5: println("woody = " + woody); 7: println("buzz = " + buzz); 8: 9: private int andy(int woody, int buzz); 11: woody *= buzz; 12: println("woody = " + woody); 13: buzz *= woody; 1 println("buzz = " + buzz); 15: return woody + buzz; 1

6 Program Nine public class QuestionableJava extends ConsoleProgram { 2: int marten = 137; 3: int faye = 42; 5: println("marten = " + marten); hannelore(faye); 7: println("marten = " + marten); 8: println("faye = " + faye); 9: marten = angus(faye, marten + faye); 11: println("marten = " + marten); 12: 13: marten = angus(marten, faye); 1 println("marten = " + marten); 15: 1 17: private void hannelore(int marten) { 18: println("marten = " + marten); 19: marten = 160; 20: 21: 22: private int angus(int marten, int faye) { 23: int dora = faye marten; 2 println("dora = " + dora); 25: return dora % 10; 2

7 Program Ten public class FrozenJava extends ConsoleProgram { 2: int anna = 16; 3: int elsa = 18; 5: anna = arendelle(anna, elsa); println("anna = " + anna); 7: println("elsa = " + elsa); 8: 9: private int arendelle(int elsa, int anna) { 11: int kristoff = elsa; 12: 13: weselton(kristoff); 1 println("kristoff = " + kristoff); 15: 1 kristoff = weselton(kristoff); 17: println("kristoff = " + kristoff); 18: println("elsa = " + elsa); 19: return anna; 20: 21: 22: private int weselton(int olaf) { 23: olaf /= 2; 2 println("olaf = " + olaf); 25: return olaf; 2