C# Lesson 3

1. C# Lesson 3 Control Statements - Selection CIS 330

2. Objectives • Learn the if statements. • Learn the switch statement. • Learn how break is used in switch statements. • Understand proper use of the goto statement CIS 330

3. The if Statement • An if statement allows you to take different paths of logic, depending on a given condition • Condition: An expression that evaluates to true or false • Basic Syntax: if (boolean expression) { statements } • When the condition evaluates to a boolean true, a block of code for that true condition will execute • else block executes if condition false CIS 330

4. The if Statement (cont) if (myInt != 0) { Console.WriteLine("Your number {0} is not equal to zero.", myInt); } else {Console.WriteLine("Your number {0} is equal to zero.", myInt); } // Multiple Case Decision if (myInt < 0 || myInt == 0) { Console.WriteLine("Your number {0} is less than or equal to zero.", myInt); } else if (myInt > 0 && myInt <= 10) { Console.WriteLine("Your number {0} is in the range from 1 to 10.", myInt); } CIS 330

5. The if Statement (cont) • In C#, the condition must evaluate to a boolean value of either true or false • Conditional OR (||) will evaluate the second sub-expression only if the first sub-expression evaluates to false • Conditional AND (&&) operator will evaluate the second sub-expression only when the first sub-expression evaluates to true CIS 330

6. The Switch Statement • The switch statement executes a set of logic depending on the value of a given parameter • Types of the values a switch statement operates on can only be booleans, enums, integral types, and strings CIS 330

7. The Switch Statement (cont) switch (myInt) {case 1:       Console.WriteLine("Your number is {0}.", myInt);       break;case 2:       Console.WriteLine("Your number is {0}.", myInt);       break;case 3:       Console.WriteLine("Your number is {0}.", myInt);       break;default:       Console.WriteLine("Your number {0} is not between 1 and 3.", myInt);       break; } CIS 330

8. C# Branching Statements CIS 330

9. C# Lesson 4 Control Statements - Loops CIS 330

10. Objectives • Learn the while loop. • Learn the do loop. • Learn the for loop. • Learn the foreach loop. • Complete your knowledge of the break statement. • Teach you how to use the continue statement CIS 330

11. The while Loop • While loop will check a condition and then continues to execute a block of code as long as the condition evaluates to a boolean value of true • Syntax: while (<boolean expression>) { <statements> } CIS 330

12. The while Loop (cont) int myInt = 0; while (myInt < 10) { Console.Write("{0} ", myInt); myInt++; } CIS 330

13. The do Loop • Similar to the while loop, except that it checks its condition at the end of the loop do {// Print A Menu       Console.WriteLine("My Address Book\n");   Console.WriteLine("A - Add New Address");   Console.WriteLine("D - Delete Address");   Console.WriteLine("M - Modify Address");   Console.WriteLine("V - View Addresses");   Console.WriteLine("Q - Quit\n"); …   Console.Write("Press Enter key to continue...");   Console.ReadLine();   Console.WriteLine(); } while (myChoice != "Q" && myChoice != "q"); // Keep going until the user wants to quit CIS 330

14. The for loop • Loop includes initialization and condition modification • Syntax: for(<initializer list>; <boolean expression>; <iterator list>) { <statements> } for (int i=0; i < 20; i++)  {    if (i == 10)       break;    if (i % 2 == 0)       continue;    Console.Write("{0} ", i);  } CIS 330

15. The foreach Loop • Loop used to iterate through the items in a list • Syntax: foreach (<type> <item name> in <list>) { <statements> } string[] names = {"Cheryl", "Joe", "Matt", "Robert"}; foreach (string person in names) {  Console.WriteLine("{0} ", person); } CIS 330