The University of Texas – Pan American CSCI 3328 Object Oriented Programming in C# Chapter 5: C# Control Statement – Part II Xiang Lian The University of Texas – Pan American Edinburg, TX 78539 lianx@utpa.edu This set of slides is revised from lecture slides of Prof. John Abraham. -- Xiang Lian

Objectives In this chapter, you will: Learn more control structures Repetition statements for, do … while Selection switch Know how to use break and continue statements to terminate the loop or current iteration Learn how to use logical operators in C#

Repetition Structure Visual C# provides 3 repetition statements while for do … while

In the Last Class: Counter Controlled while Loop int Counter =1; while (Counter <=10) { … Counter ++; }//does it 10 times

Example of for Repetition Statement Output even numbers between 2 and 10 for (int counter = 2; counter<= 10; counter+=2) { Console.Write("{0} ", counter); Console. WriteLine(); }

Discussions on for Repetition Statement for (int counter = 2; counter <= 10; counter += 2) Keywords: for "int counter" declares a counter of integer data type counter – control variable name int – control variable type Initial value of control variable – 2 Final value of control variable – 10

General Form of a for Statement for (initialization; loopContinuationCondition; increment) { statement }

Other Examples of for Statement (1) Declaring the control variable before a for statement int counter; for (counter = 2; counter <= 10; counter+=2) Console.Write("{0} ", counter); Using expressions in the for statement for (counter = x; counter <= 4*x*y; counter+=y/x)

Other Examples of for Statement (2) Increment: 1 for (counter = 2; counter <= 10; counter++) Decrement for (counter = 10; counter >= 2; counter-=2)

Example of Interest String.Format("{0, 20}", "..."); decimal amount; decimal principal = 1000; double rate = 0.05; Console.WriteLine("Year{0, 20}", "Amount on deposit"); for (int year = 1; year <= 10; year++) { amount = principal *((decimal)Math.Pow(1.0+rate, year)); } field width String.Format("{0, 20}", "...");

do…while Repetition Statements The loop body is always executed at least once int product = 1 do { product = product * 3; }while (product <=100);

Use break to Terminate Repetition Statements for (int counter = 1; counter <=10; counter ++) { if (counter == 5) break; Console.Write("{0} ", counter); } // answer: 1 2 3 4

Use continue to Terminate the Current Iteration for (int counter = 1; counter <=10; counter ++) { if (counter == 5) continue; Console.Write("{0} ", counter); } // answer: 1 2 3 4 6 7 8 9 10

In the Last Class: Selection Structures in C# if – single selection statement if … else – double selection statement switch – multiple selection statement [grade>=60] display "passed" [grade<60]

Example of Multiple Selection Statement public void 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"); break; // 60-69 default: Console.WriteLine("Grade: F"); break; // < 60 }

Expression 1 && Expression 2 Logical Operators Conditional AND operator (&&) if (gender == 'F' && age >=65) seniorFemales += 1; Expression 1 Expression 2 Expression 1 && Expression 2 false true

Logical Operators (cont'd) Conditional OR operator (||) Expression 1 Expression 2 Expression 1 || Expression 2 false true

Short-Circuit Evaluation Conditional AND operator (&&) if (gender == 'F' && age >=65) If gender is not "F", then "age >=65" will not be evaluated Conditional OR operator (||) if (gender == 'F' || age >=65) If gender is "F", then "age >=65" will not be evalutated

Boolean Logical Operators Boolean Logical AND ( & ) if (gender == 'F' & age >=65) No matter what value gender has, “age>=65” will always be evaluated Boolean Logical OR ( | ) Logical Negative ( ! )

Other Boolean Logical Operators Boolean Logical Exclusive OR (^) If both conditions are the same, then output is false Expression 1 Expression 2 Expression 1 ^ Expression 2 False True