UTPA – Fall 2012

1. CSCI 3328 Object Oriented Programming in C# Chapter 5: C# Control Statement – Part II – Exercises UTPA – Fall 2012

2. Objectives • In this chapter, you will do exercises about: • more control structures • Repetition statements • for, do … while • Selection • Switch • break and continue statements • logical operators in C#

3. Multiple Choices • Typically, ______ statements are used for counter-controlled repetition. • A. for B. while C. repetition D. until • Typically, ______ statements are used for sentinel-controlled repetition. • A. for B. while C. repetition D. until • The do … while statement tests the loop-continuation condition ________ executing the loop’s body; therefore, the body always executes at least once. • A. before B. after C. at the same time D. None of the above • The _________statement, when executed in a repetition statement, skips the remaining statements in the loop body and proceeds with the next iteration of the loop. • A. break B. exit C. continue D. return

4. Multiple Choices (cont'd) • The _____operator can be used to ensure that two conditions are both true before choosing a certain path of execution • A. and B. && C. or D. || • If the loop continuation condition in a for header is initially ___________, the for statement’s body does not execute • A. true B. false C. 0 D. 1 • Which of the following is the appropriate for statement for varying the control variable over the following sequence of values: 25, 20, 15, 10, 5? • A. for (i = 5; i<25; i+=5) B. for (i = 5; i<=25; i-=5) • C. for (i = 25; i<=5; i-=5) D. for (i = 25; i>=5; i-=5) • An infinite loop occurs when the loop-continuation condition in a while or do…while statement______. • A. never becomes true B. never becomes false C. is false D. is true for finite times

5. True/False Statements • The default label is required in the switch selection statement. • The break statement is required in every case of a switch statement • The expression ((x>y)&&(a<b)) is true if either (x>y) is true or (a<b) is true. • An expression containing the || operator is true if either or both of its operands are true. • The integer after the comma (,) in a format item (e.g., {0, 4}) indicates the field width of the displayed string. • To test for a range of values in a switch statement, use a hyphen (-) between the start and end values of the range in a case label.

6. Recall: Example of Multiple Selection Statement publicvoid CalculateGrade(int grade) { switch (grade/10) { case 9: // 90-99 case 10: // 100 Console.WriteLine("Grade: A"); break; case 8: Console.WriteLine("Grade: B"); break; // 80-89 case 7: Console.WriteLine("Grade: C"); break; // 70-79 case 6: Console.WriteLine("Grade: D"); return; // 60-69 default: Console.WriteLine("Grade: F"); break; // < 60 } }

7. True/False Statements (cont'd) • Listing cases consecutively with no statements between them enables the cases to perform the same set of statements. • Boolean logical operator (|) performs short-circuit evaluation. • The && operator has a higher precedence than the || operator. • The following statement alters the control variable from 0 to 50 in increment of 5? • for (int i=0;i<49; i+=5)

8. What Does the Code Do? public class Printing { public static void Main(string[] args) { for (inti = 1; i<=10; i++) { for (int j = 1; j<=5; j++) Console.Write ('@'); Console.WriteLine(); } } }

9. What Does the Code Do? (cont'd) // What is the output of the following code? int x=1; int y=2; if ( x == 2 && y=4) Console.WriteLine ("expression is true"); else Console.WriteLine ("expression is false"); Console.WriteLine ("y="+y);

10. Debugging Errors • The following code is to display whether integer value is odd or even Switch( value%2) { case 0; Console.WriteLine("Odd integer"); case 1: Console.Writeline("Even integer") }

11. Debugging Errors (cont'd) i=1 while (i <= 10); ++i; } --------------------------------------------------------- For (k=0.1; k!=1.0; k+=0.1) Console.WriteLine(k);

12. Write a Program • Use nested for statement to write a program to display the triangle of asterisks in outputTextBox. Use the following statements: • outputTextBox.AppendText("*"):displays asterisks one at a time • outputTextBox.AppendText(Environment.NewLine) • outputTextBox.AppendText(" "): inserts a space * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *

13. Write a Program (cont'd) • Use nested for statement to write a program to display a rectangle in outputTextBox. Use the following statements: • outputTextBox.AppendText("+") • outputTextBox.AppendText(Environment.NewLine) • outputTextBox.AppendText(" "): inserts a space + - - - - - - - - - - + | | | | | | + - - - - - - - - - - +

14. Exercises After the Class • Chapter 6 in your textbook • Self-Review Exercises • Quick Quiz • Exercises