CS 141 Topics

CS141: Topics for Week 2: Jan 22/24/26, 2018

Computer Science Headlines: ACM Tech News

Reading:

Chap 2, Section 2.2 Variables
Chap 4: Fundamental Data Types

Lab and Other Activities

Lab 2: Fundamental Data Types
In Class Practice
- Variables: Practice problems (pdf).
- Temperature conversion
- Ouch - what will you owe on your loans? Interest rate calculation.

Lecture Discussion Topics

Variables - declaring and assigning.
Primitive types
Doing Arithmetic and writing arithmetic expressions
Operator precedence
String class and operations
Input/Output:
- You must import the Scanner class at the top of the program:
  import java.util.Scanner; // import library for Scanner
- Example of how to prompt for and read a name:
  Scanner in = new Scanner(System.in); // create Scanner object System.out.print("What is your name? "); // prompt String name = in.next(); // read input System.out.println("Hello " + name+ ". "); // print results
The Process:
- Understand the problem: Know the required facts.
- Pseudocode: Write out high level solution in pseudocode.
- Stepwise Refinement:
  - Break into small manageable pieces.
  - Implement one piece at a time.
  - Debug and test each piece before going to next piece
Debug and Test: Debug and test the entire program. Check boundary cases. Make sure use interface is completely clear and not subject to user mistakes in entering inputs.

InterActivities

Section 2.2
Section 4.2, problems 2-5

Concepts and Vocabulary

Variables:
  ... variable declaration
  ... primitive data types (int, float, double, boolean, char)
  ... identifier, naming, camel case (see p. 37)
  ... reserved words
  ... variable initialization
  ... case sensitive
  ... literal, String literal
  ... scope, code block (brackets {...} )
  ... constants
  ... magic numbers

Variable Operations:
  ... variable assignment, assignment statement
  ... operator
  ... assignment statement
  ... binary arithmetic operators: +, -, *, /, %
  ... unary arithmetic operators: -, ++, --
  ... Mod function (%)
  ... integer division
  ... Math class, Math.PI, Math.random()
  ... operator precedence
  ... type conversion, cast operator

Other:
  ... stepwise refinement
  ... sytax rules vs convention
  ... statement vs expression
  ... programming style, indentation, Netbeans formatting tool
  ... comments, single line, multi-line, Javadoc

String Variables and Operations:
  ... String Class
  ... String operations
  ... escape sequence and control characters
  ... String concatenation and the + operator
  ... dot notation

Keyboard I/O, input/output:
  ... Scanner class
  ... Dialog Boxes (example: String name = JOptionPane.showInputDialog("Enter your name: " );)
  ... System.out.print, System.out.println
  ... System.out.printf, format specifier (example: System.out.printf("%.2f", price);)
  ... console
  ... standard output/input