Assignment Statement An assignment statement gives a value

Assignment Statement An assignment statement gives a value to a variable. Assignment can take several forms: x = 5; a literal (5) is assigned to x x = y + 2; the value of an expression (y + 2) is assigned to x x = z; the value of another variable (z) is assigned to x Slide 1 © 2007 Lawrenceville Press

Variable Assignment A variable can store only one value at any time. int x; x = 5; x = 10; Slide 2 x 10 5 © 2007 Lawrenceville Press

Primitive Data Types Type int double char boolean Slide 3 Storage Required 4 bytes 8 bytes 2 bytes 1 bit © 2007 Lawrenceville Press

Abstract Data Types A variable declared with a class is called an object. For example, the object spot is type Circle: Circle spot = new Circle(4); spot get. Radius() area() Slide 4 © 2007 Lawrenceville Press

C# Packages § Numerous packages are included with C# § Packages contain classes § Packages can be added to an application with an Using statement. For example, the statement Using System; makes the Scanner class and its methods accessible to the application. Slide 5 © 2007 Lawrenceville Press

Integer Division Integer division (/) is performed when both operands are integers. Only the integer portion of the quotient is returned: Slide 6 © 2007 Lawrenceville Press

Real Division Real division (/) is performed when one or both operands are type double. The entire quotient, including the decimal portion is returned: double result; result = 20. 0/7. 0; Slide 7 //result is 2. 857 © 2007 Lawrenceville Press

Modulus Division Modulus division (%) returns the remainder of a division operation: Slide 8 © 2007 Lawrenceville Press

Operator Precedence Operators in Java have the following precedence: 1. multiplication and division 2. addition and subtraction Operators of the same precedence are evaluated in order from left to right. For example, multiplication is performed first, then division, and finally addition: 5 + 6 * 4 / 2 = 17 Slide 9 © 2007 Lawrenceville Press

Changing the Order of Operations The order in which operators are evaluated can be changed by using parentheses. For example, addition is performed first, then multiplication, and finally division: (5 + 6) * 4 / 2 = 22 Slide 10 © 2007 Lawrenceville Press

Type Casting converts a number of one type to a number of a different, but compatible type. Type casting is used to: 1. make the operand types in an expression match. For example, whole. Num = (int)y * 2 2. truncate the decimal portion of a double. For example, whole. Num = (int)z 3. change the way in which a division (/) operation will be performed. For example, real. Division = (double)a / (double)b Slide 11 © 2007 Lawrenceville Press

Programming Errors § Syntax errors violate the rules of C#. § Logic errors, also called semantic errors, occur in statements that are syntactically correct, but produce undesired or unexpected results. § Run-time errors, also called exceptions, halt program execution at the statement that cannot be executed. One type of exception is called Divid. By. Zero. Execption. Slide 12 © 2007 Lawrenceville Press