» CS 145 Lecture 7 – Careful coding

CS 145 Lecture 7 – Careful coding

February 15, 2012 by Chris Johnson. Filed under cs145, lectures, spring 2012.

Agenda

relational operators
software disaster
careful coding

pseudocode
build in small pieces
test pieces in isolation
document

some problems to test

area of ring

Code

Utilities.java

package preexam1;

public class Utilities {

  // i = get area of inside
  // o = get area of outside
  // area = o - i
  
  public static double getCircleArea(double radius) {
    return Math.PI * radius * radius;
  }

  /**
   * Gets the area of a ring defined by its inner and outer radii.
   * @param innieRadius The inner circle's radius
   * @param outieRadius The outer circle's radius
   * @return The area of the ring
   */
  public static double getRingArea(double innieRadius, double outieRadius) {
    return getCircleArea(outieRadius) - getCircleArea(innieRadius);
  }
  
  public static boolean equalEnough(double a, double b) {
    double difference = a - b;
    return Math.abs(difference) < 0.000001;
  }
  
  public static void main(String[] args) {
    System.out.println(0 == getCircleArea(0.0));
    System.out.println(Math.PI == getCircleArea(1.0));
//    System.out.println(113.097335529233 == getCircleArea(6.0));
    System.out.println(equalEnough(113.097335529233, getCircleArea(6.0)));
    
    System.out.println(0 == getRingArea(5.0, 5.0));
    System.out.println(equalEnough(34.5575191894877, getRingArea(5.0, 6.0)));
  }
}

Haiku

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