Need help writing an int to roman numeral converter using only if, if else, and switch statements

Question

Here is the code:

public String ToRoman(int number)
{

    if ((number < 1 || (number > 3999)))

        if (number >= 1000) return "M" + ToRoman(number - 1000);

        if (number >= 900) return "CM" + ToRoman(number - 900); 

        if (number >= 500) return "D" + ToRoman(number - 500);

        if (number >= 400) return "CD" + ToRoman(number - 400);

        if (number >= 100) return "C" + ToRoman(number - 100);            

        if (number >= 90) return "XC" + ToRoman(number - 90);

        if (number >= 50) return "L" + ToRoman(number - 50);

        if (number >= 40) return "XL" + ToRoman(number - 40);

        if (number >= 10) return "X" + ToRoman(number - 10);

        if (number >= 9) return "IX" + ToRoman(number - 9);

        if (number >= 5) return "V" + ToRoman(number - 5);

        if (number >= 4) return "IV" + ToRoman(number - 4);

        if (number >= 1) return "I" + ToRoman(number - 1);

    Scanner myKeyboard = new Scanner (System.in);
    System.out.println("Enter the integer: ");
    number = myKeyboard.nextInt();

    myKeyboard.close();


    }
}

The problem im having is that i get an error saying "The method must return a result type string".

You need *two* functions; one to get the input, the other to convert to Roman numerals. — Eric Brown, Oct 02 '13 at 22:02

Matt Bryant · Answer 1 · 2013-10-02T21:59:11.767

You need a helper function:

public String ToRomanWrapper()
{
    Scanner myKeyboard = new Scanner (System.in);
    System.out.println("Enter the integer: ");
    number = myKeyboard.nextInt();
    myKeyboard.close();
    return ToRoman(number);
}

public String ToRoman(int number){
    if ((number < 1 || (number > 3999)))
        return "INVALID"
    if (number >= 1000) return "M" + ToRoman(number - 1000);
    if (number >= 900) return "CM" + ToRoman(number - 900); 
    if (number >= 500) return "D" + ToRoman(number - 500);
    if (number >= 400) return "CD" + ToRoman(number - 400);
    if (number >= 100) return "C" + ToRoman(number - 100);            
    if (number >= 90) return "XC" + ToRoman(number - 90);
    if (number >= 50) return "L" + ToRoman(number - 50);
    if (number >= 40) return "XL" + ToRoman(number - 40);
    if (number >= 10) return "X" + ToRoman(number - 10);
    if (number >= 9) return "IX" + ToRoman(number - 9);
    if (number >= 5) return "V" + ToRoman(number - 5);
    if (number >= 4) return "IV" + ToRoman(number - 4);
    if (number >= 1) return "I" + ToRoman(number - 1);
    return "INVALID"
}

Alternatively, if you cannot define new functions, you can do this in the same function:

public String ToRoman(int number)
{                                                                                                         
    if ((number < 1 || (number > 3999)))
    {                           
        Scanner myKeyboard = new Scanner (System.in);
        System.out.println("Enter the integer: ");
        number = myKeyboard.nextInt();
        myKeyboard.close();     
        return ToRoman(number); 
    }                           
    else if (number >= 1000) return "M" + ToRoman(number - 1000);
    else if (number >= 900) return "CM" + ToRoman(number - 900); 
    else if (number >= 500) return "D" + ToRoman(number - 500);
    else if (number >= 400) return "CD" + ToRoman(number - 400);
    else if (number >= 100) return "C" + ToRoman(number - 100);            
    else if (number >= 90) return "XC" + ToRoman(number - 90);
    else if (number >= 50) return "L" + ToRoman(number - 50);
    else if (number >= 40) return "XL" + ToRoman(number - 40);
    else if (number >= 10) return "X" + ToRoman(number - 10);
    else if (number >= 9) return "IX" + ToRoman(number - 9);
    else if (number >= 5) return "V" + ToRoman(number - 5);
    else if (number >= 4) return "IV" + ToRoman(number - 4);
    else if (number >= 1) return "I" + ToRoman(number - 1);
}

I'm not sure why you'd want to do this though. Reading the input in the same function that handles the input would be really nasty.

Okay I'm starting to see why this wasn't working, it's just now my scanner is saying that it cannot be resolved to a type. Thank you for your time and help by the way. — user2840309, Oct 02 '13 at 22:14

Need help writing an int to roman numeral converter using only if, if else, and switch statements

1 Answers1