1. Introduction to Computer Programming
CS 126
Lecture 3
Zeke Maier

2. Plan for Today Questions Administrivia Data Types and Expressions
Assignment

3. Questions Steve Jobs Products? Macworld Health? iPod iPhone iTunes
MacBook
Macworld
iTunes Store selling DRM free music
Weight Loss, Hormone Imbalance, More Complex…, 6 month leave of absence, Cancer?
Steven Paul Jobs 1955, is the American co-founder, Chairman, and CEO of Apple Inc. and the former CEO of Pixar Animation Studios.
In the late 1970s, Jobs, with Apple co-founder Steve Wozniak, created one of the first commercially successful personal computers. In the early 1980s, Jobs was among the first to see the commercial potential of the mouse-driven graphical user interface
Jobs's history in business has contributed greatly to the myths of the quirky, individualistic Silicon Valley entrepreneur, emphasizing the importance of design while understanding the crucial role aesthetics play in public appeal. His work driving forward the development of products that are both functional and elegant has earned him a devoted following.[12]
Jobs is currently on a leave of absence from Apple due to health issues.[13
is considered one of Silicon Valley's leading egomaniacs.
Jobs has always aspired to position Apple and its products at the forefront of the information technology industry by foreseeing and setting trends, at least in terms of innovation and style.
Digital Rights Management (DRM)-free.
End of march
Other musinc playing devices (Zune) can play music bought from the iTunes Store (codecs on song required it to be played by a Mac product)
DRM (restrcit copying and other illeagal activities)

4. Administrivia http://students.cec.wustl.edu/~ejm3/ TAs! CEC accounts
Lab assignments
Readings

5. Data Types Everything in Java has a type Primitive Types
type: “kind of thing”
Primitive Types
int: Integer number: 5, 10, 15
double: Decimal number: 5.15, 10.25
boolean: true or false
String: a string of characters: “Hello World”

6. Expressions Expression: anything that has a value Order of operations
infix expression syntax
operators between operands
Order of operations
Evaluate left to right under the rules
Negation (-)
Multiplication(*), Division(/), & Modulus(%)
Addition(+), Subtraction(-)

7. Expression Trees Evaluated left to right and bottom to top * + % 8 518 5

8. String Concatenation Boolean Expressions
+ operator will combine strings together
Other primitive values will be converted to strings when concatenation occurs
Boolean Expressions
Expressions that evaluate to true or false
&& and operator
|| or operator
! not operator
== equals operator

9. Variables A symbol which can hold a value of a particular type
int age; String myName; double cars;
Assign a value of a variable
int age = 24;
String myName = “Zeke”;
double cars = 0.5;
Think of a variable as a container with the "right shape" to hold a value of the declared type
Assign the value of an expression to a variable
double money = (3 * 1.50);

10. Assigning New Values Variables can be reassigned a new value
int age = 24;
age = 25;
int age = 24;
age = age + 1;
final keyword forces variable to retain initial value
final variables, called constants, have all uppercase names
final int AGE = 24;
AGE = 25; //Error

11. Composition Combining small blocks of code
How could we compose these three statements into a single statement?
int age;
age = 24;
System.out.print(age);

12. Naming Abstraction Circle Area Example
Giving names to values: using variables
What are some advantages?
Choose meaningful names for variables!
Circle Area Example
It saves us from retyping the value all the time and makes programs easier to read.

13. Assignment No Class Monday Readings Wednesday
AD Chapter 2, Chapter 7:
KG Notes