CSCI 3328 Object Oriented Programming in C# Chapter 5: C# Control Statement – Part II – Exercises 1 Xiang Lian The University of Texas Rio Grande Valley Edinburg, TX

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# 2

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 3

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) 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 4

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 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. 5

Recall: Example of Multiple Selection Statement public void CalculateGrade(int grade) { switch (grade/10) { case 9: // case 10: // 100 Console.WriteLine("Grade: A"); break; case 8: Console.WriteLine("Grade: B"); break; // case 7: Console.WriteLine("Grade: C"); break; // case 6: Console.WriteLine("Grade: D"); return; // default: Console.WriteLine("Grade: F"); break; // < 60 } 6

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) 7

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

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); 9

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") } 10

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

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 12 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *

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 | |

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

15