3 C# Control Statements

1. 3 C# Control Statements Dr. John P. Abraham Professor UTPA

2. Control statements • Linear (sequential) program execution • Selection structure and repetition structure • Structured programming • Controlled entry and exit out of a module. • Avoid goto statements

3. Selection structures in C# • If – single selection statement • If..else – double selection statement • Swich – multiple – selection satement

4. Examples: if (grade >= 60) Console.writeline(“Passed!”); If (grade >=0) Console.writeline(“Passed!”); else Console.writeline(“Failed!”); Conditional Operator Console.writeline(grade >= 60 ?“Passed!” : “Failed!”);

5. Nested if (grade >=90) Console.writeline(“A”); else if (grade >=80) Console.writeline(“B!”); … else Console.writeline(“F!”);

6. Repetiton Structure - while Read LCV (initialize) While (condition) { Block Read LCV again (change value) }

7. Example length = Convert.ToInt16(Console.ReadLine()); while (length > 0) { Console.Write("Enter Height of the Wall: "); height = Convert.ToInt16(Console.ReadLine()); PaintAWall thisWall = new PaintAWall(length, height, pricePerGal); thisWall.CalculateCost(ref paintCost,ref laborCost,ref galPaint, ref sqFt); Console.Write("Enter Length and Height for Wall # : “ + Convert.ToString(numWalls+1)); Console.Write("\nEnter Length of the Wall (0 to quit): "); length = Convert.ToInt16(Console.ReadLine()); }

8. Counter Controlled vs sentinel controlled • A while loop, use LCV as a counter • Counter =1 • While (counter <=10) • { • … • Counter ++ • }//does it 10 times • Sentinel controlled is good when one does not know exact number of times to execute a loop

9. Explicitly and Implicitly converting between simple types • Integer and integer division yields integer result. • Suppose average is a floating point number: • Average = total/num. Average will only get an integer if total and num are integers. int sum = 200, num = 3; float av; av = sum / num; Console.WriteLine(av); Will print 66

10. Unary Cast Operator int sum = 200, num = 3; float av; av = (float) sum / num; Console.WriteLine(av); Will print 66.6666 Float/float or float/int or int/float will yield a float. C# implicitly promotes the one int to float.

11. Nested control statements • See example of a multiplication table generation class MultiplicationTable { static void Main(string[] args) { int i=2, j, k; while (i <= 12) { for (j = 1; j <= 10; j++) { Console.WriteLine(i + " x " + j + " = " + i * j ); } Console.WriteLine("\n"); i++; } } } }

12. Switch Statements