CS 302 - Week 3 Jim Williams

Learning and Effort Influence Intelligence "...effort and difficulty, that's when their neurons are making new connections, stronger connections. That's when they're getting smarter." - Carol Dweck https://www.ted.com/talks/carol_dweck_the_power_of_believing_that_you_can_improve

P1 Milestone 2 due Thursday 8:00am Week 3 P1 Milestone 2 due Thursday 8:00am Commenting Example Exam Confirmation and Accommodation requests due by Friday CS Learning Center In CS Building, above entrance to Union South https://cs302-www.cs.wisc.edu/wp/contact-3/#CSLearningCenter

Eclipse IDE (Integrated Development Environment) Interpreter Translator Users Editor (Virtual) Machine Compiler Hello.java Hello.class Computer Files Programmer

Programming Errors Syntax/Compile time Runtime & Logic Files Editor (Virtual) Machine Compiler Hello.java Hello.class Computer Files Programmer

Programming Errors Syntax compiler error Logic program runs but provides wrong values Runtime program crashes or throws exception

Debugging print statements Java Visualizer Breakpoints in Eclipse https://en.wikipedia.org/wiki/Debugging

What is print out? a char choice = 'a'; switch (choice) { case 'a': System.out.print("a"); case 'b': System.out.print("b"); break; default: System.out.print("other"); } a b ab other

? : operator (not recommended) condition ? <true value> : <false value> What is out? String out = "don't know"; boolean sunny = false; out = sunny ? “sunny” : “cloudy”; out:don't know out:sunny out:cloudy

Scanner num: 0 str4: line str4: line note. num: 3 str4: String note = "Hmm\na 3\nline note."; Scanner input = new Scanner( note); int num = 0; String str1 = input.nextLine(); String str2 = input.next(); if ( input.hasNextInt()) { num = input.nextInt(); } String str4 = input.nextLine();

char - Which will compile? 1, 2, 3 1, 3 1 2, 3 int intValue = 0; char aChar = 'B'; intValue = aChar; // 1 aChar = intValue + 1; // 2 aChar = '\u0041'; // 3

Increment && Decrement i = i + 1; i += 1; i++; ++i; i = i -1; i -= 2; --i; i--;

Week 3 Exam Confirmation and Accommodation Requests Due Tomorrow

Puzzle int i = 5, j = 2, k; j += 3; k = i++ + --j; After this executes, what are the values in i, j and k?

Puzzle int i = 5, j = 2, k; j = i + 3; k = i++ + --j - 1; After this executes, what are the values in i, j and k?

Floating Down A Circular River?! http://www.thehiltonorlando.com/discover/pools-and-lazy-river/

How many times will this execute? 1 until num > 0 until num <= 0 Scanner input = new Scanner( System.in); int num; int sum = 0; do { num = input.nextInt(); sum += num; } while ( num > 0);

Body of While will execute... boolean finished = false; while ( !finished) { String line = input.nextLine(); if ( line.equals("done")) { finished = true; } else { System.out.println("echo:" + line); } until "done" is input never forever other?

How many "hello"? for ( int a = 0; a <= 5; a++) { System.out.print("hello "); } 4 5 6 other?

How many "hello"? for ( int a = 5; a >= 1; a++) { System.out.print("hello "); } 4 5 6 other?

How many "bye"? for ( int i = 1; i <= 5; i++) { for ( int j = 2; j < 6; j++) { System.out.print("bye "); } 5 9 20 other?

What does this print? for ( int i = 1; i <= 5; i++) { 1,1 1,2 1,3 2,1 2,2 2,3 3,1 3,2 3,3 4,1 4,2 4,3 5,1 5,2 5,3 1,1 2,1 3,1 1,2 2,2 3,2 1,3 2,3 3,3 1,4 2,4 3,4 1,5 2,5 3,5 for ( int i = 1; i <= 5; i++) { for ( int j = 1; j <= 3; j++) { System.out.print(i+","+j+" "); } System.out.println();

What is the value of count? 3 9 12 other int count = 0; for ( int i = 1; i < 4; i++) { for ( int j = 6; j > 3; j--) { count += 1; } System.out.println("count=" + count);

What is the value of sum? 3 9 12 other int sum= 0; boolean done = false; for ( int i = 1; i < 4 && !done; i++) { for ( int j = 6; j > 3; j--) { if ( j > 4) continue; sum += 1; } if ( i == 3) break; System.out.println("sum=" + sum); 3 9 12 other