ITEC 120 2009spring ibarland nokie jmdymacek

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lect01c
values; variables

We have already seen two types of values:
  String:    "hello", "hi", "a", ""
  int:       43, -7, 2, 0
There is one more we'll see:
  double:    2.3, -7.0, 3.0e8, 6.022e23
  ("double" means "double-precise *estimate* to the actual desired number";
   we'll talk more on that later.)


Examples:
  System.out.print( "hello" )
  System.out.print( 7 );
  System.out.print( "spy " + 7 );   // Note implicit conversion (Integer.toString(7))


Declaring a variable:
  examples




A program: What's the volume of an ice-cream cone, 9cm high, 2cm radius?
We are told by our math buddies that the formula is 1/3*base*height.
The base  will be pi*2*2 = ~12.56;     1/3 * ~12.56 * 9 = ~37.68
        System.out.println( "The volume of an ice-cream-cone " );
        System.out.println( "with height 9cm and radius 2cm is " );
        System.out.println( 1/3 * (3.14*2*2) * 9 );


UH-OH: use 1.0/3.0.  We'll see why later.
BUT: What if we suddenly decide we instead want height 12, radius 1.2?

public class Lect01cTester {
    public static void main( String[] args ) {
        double r;
        r = 1.2;
        double h;
        h = 12.0;
        
        double base;
        base = 3.14 * r * r;
        
        System.out.println( "The volume of an ice-cream-cone " );
        System.out.println( "with height " + h + "cm and radius " + r + "cm is " );
        System.out.println( 1.0/3.0 * base * h );
        }
    }

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©2009, Ian Barland, Radford University Last modified 2009.Jan.27 (Tue)

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