3 C# Control Statements

Dr. John P. AbrahamProfessor

UTPA

Control statements

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

Selection structures in C#

• If – single selection statement• If..else – double selection statement• Swich – multiple – selection satement

Examples:

if (grade >= 60) Console.writeline(“Passed!”);

If (grade >=0) Console.writeline(“Passed!”);

elseConsole.writeline(“Failed!”);

Conditional OperatorConsole.writeline(grade >= 60 ?“Passed!” : “Failed!”);

Nested

if (grade >=90) Console.writeline(“A”);

else if (grade >=80) Console.writeline(“B!”);…else

Console.writeline(“F!”);

Repetiton Structure - while

Read LCV (initialize)While (condition){

BlockRead LCV again (change value)

}

Examplelength = 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()); }

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

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

Unary Cast Operatorint sum = 200, num = 3;

float av; av = (float) sum / num; Console.WriteLine(av);Will print 66.6666Float/float or float/int or int/float will yield a

float.C# implicitly promotes the one int to float.

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++; } } }}

Switch Statements