1. Control Structures Lecture 3 Instructors: Fu-Chiung Cheng ( 鄭福炯 ) Associate Professor Computer Science & Engineering Tatung University email: cheng@cse.ttu.edu.tw http:// www.cse.ttu.edu.tw/~fccheng

2. Contents: Control Structures Decision  Using if and if...else  Nested if Statements  Shortcut if Statements  Using switch Statements Repetition  Looping: for, while, and do  Nested loops  Using break and continue

3. Decisions if Statements switch Statements Shortcut if Statements

4. if Statements Format: Format: if (booleanExpression) { statement(s); statement(s);} Example: Example: if ((i >= 0) && (i = 0) && (i <= 10)) System.out.println("i is between 0 and 10"); System.out.println("i is between 0 and 10");

5. The if...else Statement Format: Format: if (booleanExpression) { statement(s)-for-the-true-case; statement(s)-for-the-true-case;}else{ statement(s)-for-the-false-case; statement(s)-for-the-false-case;}

6. if...else Example if (radius >= 0) { area = radius*radius*PI; area = radius*radius*PI; System.out.println("The area for the System.out.println("The area for the circle of radius " + radius + " is " + area); circle of radius " + radius + " is " + area);}else{ System.out.println("Negative input"); System.out.println("Negative input");}

7. Nested if Statements Example 3.1: Using Nested if Statements This program reads in year and loan amount and computes the monthly pay and total pay. The interest rate is determined by year. TestIfElse

8. Shortcut if Statements if (x > 0) y = 1 else y = -1; is equivalent to y = (x > 0) ? 1 : -1;

9. switch Statements switch (year) { case 7: interestRate = 7.25; case 7: interestRate = 7.25; break; break; case 15: interestRate = 8.50; case 15: interestRate = 8.50; break; break; case 30: interestRate = 9.0; case 30: interestRate = 9.0; break; break; default: System.out.println( default: System.out.println( "Wrong Year, enter 7, 15, or 30"); "Wrong Year, enter 7, 15, or 30");}

10. switch Statement Flow Chart

11. Repetitions for Loops while Loops do Loops break and continue

12. for Loops Format: Format: for (control-variable-initializer; continue-condition; adjustment-statement) continue-condition; adjustment-statement){ //loop body; //loop body;} Example: Example: int i; for (i = 0; i<100; i++) { System.out.println("Welcome to Java!” + i); System.out.println("Welcome to Java!” + i);} // for (int i = 0; i<100; i++) // for (int i = 0; i<100; i++)

13. for Loop Flow Chart

14. for Loop Examples Examples for using the for loop: F Example 3.2: TestSum.java TestSum TestMulTable F Example 3.3: TestMulTable.java

15. while Loops Format: Format: while (continue-condition) { // loop-body; // loop-body;} Example 3.4: TestWhile.java Example 3.4: TestWhile.java TestWhile

16. while Loop Flow Chart

17. do Loops Format: Format:do{ //loop body; //loop body; } while (continue-condition)

18. do Loop Flow Chart

19. The break Keyword

20. The continue Keyword

21. Using break and continue Examples for using the break and continue keywords: F Example 3.5: TestBreak.java F Example 3.6: TestContinue.java TestBreak TestContinue