New answers only
outcomes for this lab:
Say My Number
You will produce a short, elegant, recursive algorithm that spells out any number between 1 and 2.1 billion.
Allow the user to input a number in the range from 1 to 2.1 billion (a positive 32-bit int), then spell out the number (e.g. 123456 would output "one hundred twenty three thousand four hundred fifty six").
Use a recursive method "say(n)" where say(n) returns the string corresponding to the input integer n.
The beauty of recursion is that this can be done with just a few if statements and switch/case values (about 30 or so total), thanks to the way we read numbers (the number 123,123,123 is spoken the same as a single 123, but with a few "place" words - million, thousand, etc.).
Deliverable:
Saymynumber.java
package HomeworkLib;
import java.text.DecimalFormat;
import java.util.Scanner;
public class Saymynumber {
private static final String[] tensNames = {
"",
" ten",
" twenty",
" thirty",
" forty",
" fifty",
" sixty",
" seventy",
" eighty",
" ninety"
};
private static final String[] numNames = {
"",
" one",
" two",
" three",
" four",
" five",
" six",
" seven",
" eight",
" nine",
" ten",
" eleven",
" twelve",
" thirteen",
" fourteen",
" fifteen",
" sixteen",
" seventeen",
" eighteen",
" nineteen"
};
private Saymynumber() {}
private static String convertLessThanOneThousand(int number) {
String soFar;
if (number % 100 < 20){
soFar = numNames[number % 100];
number /= 100;
}
else {
soFar = numNames[number % 10];
number /= 10;
soFar = tensNames[number % 10] + soFar;
number /= 10;
}
if (number == 0) return soFar;
return numNames[number] + " hundred" + soFar;
}
public static String convert(long number) {
// 0 to 999 999 999 999
if (number == 0) { return "zero"; }
String snumber = Long.toString(number);
// pad with "0"
String mask = "000000000000";
DecimalFormat df = new DecimalFormat(mask);
snumber = df.format(number);
// XXXnnnnnnnnn
int billions = Integer.parseInt(snumber.substring(0,3));
// nnnXXXnnnnnn
int millions = Integer.parseInt(snumber.substring(3,6));
// nnnnnnXXXnnn
int hundredThousands = Integer.parseInt(snumber.substring(6,9));
// nnnnnnnnnXXX
int thousands = Integer.parseInt(snumber.substring(9,12));
String tradBillions;
switch (billions) {
case 0:
tradBillions = "";
break;
case 1 :
tradBillions = convertLessThanOneThousand(billions)
+ " billion ";
break;
default :
tradBillions = convertLessThanOneThousand(billions)
+ " billion ";
}
String result = tradBillions;
String tradMillions;
switch (millions) {
case 0:
tradMillions = "";
break;
case 1 :
tradMillions = convertLessThanOneThousand(millions)
+ " million ";
break;
default :
tradMillions = convertLessThanOneThousand(millions)
+ " million ";
}
result = result + tradMillions;
String tradHundredThousands;
switch (hundredThousands) {
case 0:
tradHundredThousands = "";
break;
case 1 :
tradHundredThousands = "one thousand ";
break;
default :
tradHundredThousands = convertLessThanOneThousand(hundredThousands)
+ " thousand ";
}
result = result + tradHundredThousands;
String tradThousand;
tradThousand = convertLessThanOneThousand(thousands);
result = result + tradThousand;
// remove extra spaces!
return result.replaceAll("^\\s+", "").replaceAll("\\b\\s{2,}\\b", " ");
}
/**
* testing
* @param args
*/
public static void main(String[] args) {
Scanner sc= new Scanner(System.in);
System.out.println("Please enter a number: ");
long number= sc.nextInt();
System.out.println("*** " + Saymynumber.convert(number));
}
}
OUTPUT:
Please enter a number:
52346647
l*** fifty two million three hundred forty six hundred forty seven
New answers only outcomes for this lab: Recursive concepts Uses for recursion Infinite recursion Problem solving...