1. Operators and Expressions
Chapter 2
Operators and Expressions

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4. Operators Operation Operator Rank Addition + 2 Subtraction - 2
Multiplication * 1
Division / 1

5. More on operators Unary – one operand Binary – two operands
Ternary – one of two possible results

6. Addition When you want to add 5 and 10 5+10 using variables: num1 = 5;
total = num1 + num2;

7. Addition How to use: int student1 = 100; int student2 = 95;
int sum;
sum = student1+student2+student3;
Console.WriteLine(“s1 = {0}, s2 = {1}, s3 = {2}”, student1, student2, student3);
Console.Writeline(“sum = “ + sum);

8. Program style // declare section int student1; int student2;
int sum;
// input section
student1=100;
student2=95;
student3=96;
// calculate section
sum = student1+student2+student3;
// results section
Console.WriteLine(“s1 = {0}, s2 = {1}, s3 = {2}”, student1, student2, student3);
Console.Writeline(“sum = “ + sum);

9. Subtraction double salary = 255.32; double benefits = 26.66;
double netsal;
netsal = salary – benefits;
Console.WriteLine(“Sal={0}, Ben={1}, Net={2}”, salary, benefits, netsal);

10. Multiplication double grade=4.0; double credits=3.0; double qualpts;
Console.WriteLine(“With a grade of {0}, and {1} credits, you earned {2} QP”, grade, credits, grade * credits);

11. Division
As with the other operators, merely place it between two numeric variables
int hrsofsleep;
int hrsofstudy;
double grade = hrsofstudy / hrsofsleep;

12. Allowing User Input double grade;
grade = double.Parse(Console.ReadLine());
(Or int or decimal )
Console.Write(“Please enter numeric Grade ”);

13. Formatting Output When you want to print money without $:
netsal =
Console.WriteLine(“Net Salary {0:N2}”, netsal)
Result: Net Salary 2,600.45
Console.WriteLine(“Net Salary {0:C}”, netsal)
Result: Net Salary $2,600.45

14. Increment and Decrement
int age = 2;
age = age + 2; what is the value of age?
old = age++; (called postfix)
same as old=age; and then age=age+1
old=++age;
Same as age=age+1; and then old=age;

15. Ternary Operator exp1 ? exp2 : exp3 If exp1 is true, do exp2
If exp1 is false, do exp3