// Format.java
// Solution to Short Assignment #3 by THC.
// Asks the user for a number x and a number of decimal places.
// Prints the square of x to the requested number of decimal places,
//    with trailing 0s trimmed off.
// Note: You can ask for as many places as you like, but the
//    DecimalFormat class will cut you off at 16 places. Also, if
//    you ask for a negative number of decimal places, you get 0 places.

import java.util.Scanner;
import java.text.DecimalFormat;

public class Format {
  public static void main(String[] args) {
    double x; // number to take square of
    int places; // how many decimal places
    
    // Create a Scanner for keyboard input.
    Scanner input = new Scanner(System.in);

    // Get the number to take the square of from the user.
    System.out.print("What number do you want the square of? ");
    x = input.nextDouble();

    // Now find out how many decimal places.
    System.out.print("How many decimal places? ");
    places = input.nextInt();

    // Starting with a pattern of "0.", append a "#" for each decimal
    // place that the user has asked for.
    // We use a for loop here, but we could just as well have used
    // a while loop.
    String pattern = "0.";
    for (int i = 1; i <= places; i++)
      pattern = pattern + "#";

    // Now pattern is "0." followed by places "#" symbols.
    // Make a DecimalFormat object fmt that uses this pattern.
    DecimalFormat fmt = new DecimalFormat(pattern);

    // Print out the result, using the format now contained in fmt.
    // We can just use x * x as the parameter to fmt.format, since that
    // parameter is supposed to be any double.
    System.out.println("To " + places + " decimal places, " + x
        + " squared = " + fmt.format(x * x));
  }
}