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Sep 2012
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#### Calculating the area of a circle from the radius.

Somewhere hidden in this code, you might be able to find the answer to a problem typically set by academics.
Java Code:
```/**
* This works out the area of a circle as PI * Radius
* squared. Please carefully look  through the source
* code to see which bit is doing the mathematics. I
* don't think this provides perfect answers, but it's
* close enough.
*
* @author Shaun B
* @version 2012-10-28
**/
import java.lang.Math;
import java.util.Scanner;
public class exerciseOne
{
// This is a constant available at a class level
static final double PI = Math.PI;
// This will read in our keyboard inputs via the Scanner utility
static Scanner keyboardInput = new Scanner(System.in);
// This will tell the main routine to continue running:
static boolean run = true;
public static void main(String[] args)
{
// Local variables available only in this scope:
float area = 0.00f;
// Our main loop (will continue until run is set to false):
while (run)
{
System.out.println("or enter 0 (zero) to exit this demonstration.");
System.out.print("C:\\>");
// Because we're using the scanner to read in numbers, we
// need to try it to catch any errors:
try
{
// Gets a new instance of the keyboard scanner, which takes in
// system inputs from the keyboard, and takes the next integer
// value
}
// This will catch an error in case there is a problem with the
// keyboard entry, ie, it is not an integer number or has
// illegal characters such as alpha characters:
catch (Exception e)
{
System.err.println("Illegal keyboard input in main class");
run = false;
// This will promptly exit the Java run-time environment:
System.exit(0);
}
{
System.out.println("Goodbye");
run = false;
break;
}
else
{
// This answers the criteria on the worksheet in exercise one:
// Calculates the area of the circle:
System.out.print("The area is: ");
// Outputs the value as a decimal number:
System.out.format("%f\n",area);
}
}
System.exit(0);
}
}```

Have fun,

Shaun.
Last edited by Shaun_B; October 30th, 2012 at 01:48 PM. Reason: Needed a bit of editing.