For a problem in my Java course we must make a program that calculates roman num
ID: 3675623 • Letter: F
Question
For a problem in my Java course we must make a program that calculates roman numerals. The program asks the user what operation to perform and for two operands. Most of the code is already done, but I am having a problem getting the char getOperator() and boolean doCalculation() methods to work. When I run the program it asks for the operator and will continue regardless of whether the input is valid or not (if I enter q to quit it does not quit). Furthermore, if I enter roman numerals for calculation it always returns the answer 0. I'm a beginner and a little stumped as to how to get it working. Any help in fixing the code would be greatly appreciated. I have copy and pasted the code below. The two methods I'm getting errors with are toward the top of it.
package roman_calculator;
import java.util.Scanner;
public class RomanCalculator {
Scanner scan = new Scanner(System.in);
boolean doCalculation()
{
char operand, operator = getOperator();
if (operator == 'q')
return false;
int operand1 = getOperand(1),operand2 = getOperand(2);
int answer = doArithmetic(operand1, operand2, operator);
String sAnswer = convert_to_Roman(answer);
System.out.println("Answer = " + answer);
return true;
}
char getOperator()
{
System.out.println("Enter operation: + - * / q (q ==> quit): ");
String input = scan.next();
return 0;
}
int getOperand(int which)
{
System.out.println("Enter operand " + which + ":");
String op = scan.next();
return convert_from_Roman(op);
}
String convert_to_Roman(int value)
{
{
String roman = " ";
while (value > 0 && value < 4000)
switch (value)
{
case 1000:
roman += 'M';
break;
case 500:
roman += 'D';
break;
case 100:
roman += 'C';
break;
case 50:
roman += 'L';
break;
case 10:
roman += 'X';
break;
case 5:
roman += 'V';
break;
case 1:
roman += 'I';
break;
}
return roman;
}
}
int convert_from_Roman(String value)
{
String s = value.toUpperCase();
s = s.trim();
int len = s.length();
int total = 0;
for (int i = len-1; i >= 0; i--)
{
char c = value.charAt(i);
switch (c)
{
case 'M':
total += 1000;
break;
case 'D':
total += 500;
break;
case 'C':
total += 100;
break;
case 'L':
total += 50;
break;
case 'X':
total += 10;
break;
case 'V':
total += 5;
break;
case 'I':
total += 1;
break;
}
}
return total;
}
int doArithmetic(int operand1, int operand2, char operator)
{
switch (operator)
{
case '+':
return operand1 + operand2;
case '-':
return operand1 - operand2;
case '*':
return operand1 * operand2;
case '/':
return operand1 / operand2;
}
return operator;
}
public static void main(String[] args)
{
RomanCalculator rc = new RomanCalculator();
while (rc.doCalculation())
{
System.out.println();
}
System.out.println("Finished Roman Computations");
}
}
Explanation / Answer
Answers:)
1. in the below lines:
System.out.println("Enter operation: + - * / q (q ==> quit): ");
String input = scan.next();
you are returning string but you are returning it to char so fix it as below:
System.out.println("Enter operation: + - * / q (q ==> quit): ");
String input = scan.next();
System.out.println("input="+input);
char c = input.charAt(0);
return c;
2. char c = value.charAt(i); in convert_from_Roman() is not giving the uppercase so do it as below:
char c = value.charAt(i);
c=Character.toUpperCase(c);
3. check your logic for convert_from_Roman because it is giving 6 even for IV
4. convert_to_Roman() is in infinite loop as while (value > 0 && value < 4000) is nver false
check your logic for this
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