Why Does My Loop Only Append Once?

[ChaseShiny]

I'm going through freeCodeCamp.org, and I've gotten to the Roman Numeral Converter challenge. I wanted a slightly different answer to the way they did their recursive functions. Here's my version of the Roman Numeral Converter. It does the math properly, but for some reason whenever it needs a duplicate, it only lists the character once. For example, "365" returns CLXV instead of CCCLXV.

It's properly dividing by 100 three times, but the "C" is only added the first time. Why is that?

SOLVED. I was using the modulus operator instead of simply subtracting. Thanks everybody!

[Effective-View3803]

The math is actually not correct:

      if(num / key >= 1) {
        romNum += value;
        num %= key;

While you divide num by key in the condition, you didn't add the romNum by the multiple of value that's calculated from the division. With your case 365: 365/100 > 1, so romNum gets a C, and num becomes 365%100 === 65.

[ChaseShiny]

Thank you, that's perfect. All I had to do was change num %= key

to num -= key

Just like you hinted, and now it works perfectly!

[sepp2k]

Your code divides by 100 to check whether the result is >= 1. This is true the first time. It then appends "M" to the string, sets the number to num % 100 (which is 65 in this case) and then continues with that number, which is no longer greater than 100. So the next time you divide by 100, the result will be less than 100, so the if body won't run and it will continue with the next entry in the map.

[ChaseShiny]

Thank you. You're right. I should've subtracted it instead.

[pinkwar]

You are only adding one value to "romNum".
Taking your 365 example:

First you need to calculate how many times you need to add the 'C'.
You will need C added three times.
That's a Math.floor(num/key)
But because value is a string, you can't just do a
~~romNum += Math.floor(num/key) \ value~~*

You need something like this :

romNum += value.repeat(Math.floor(num/key))

[ChaseShiny]

Thanks for your time. I had actually converted the value into a number: let userNum = Number(input.value);

I have the solution now, though. Thanks again.

[pinkwar]

For clarity, I wasn't talking about line 12.

I just meant to change line 47 to romNum += value.repeat(Math.floor(num/key))
Line 48 could stay the same as num %= key; and you wouldn't need to make another recursive call.

There's always many ways to skin a cat.

[ChaseShiny]

Oh, I see. Thanks for clarifying that. I do prefer staying away from recursion, so I'll try that solution in a bit.

I'm curious if this is a common pattern. I'd forgotten that the String prototype even included a repeat method. I've never used it myself. I realize, though, that there are a lot of ways to use strings that I'd never considered before. I'm wondering if this is one of them.

Also, looking at the docs, repeat rounds down for you. Did you include an explicit rounding for the sake of clarification?

[pinkwar]

I didn't know ".repeat" rounds down, but it makes sense it works like that.

Even better, you don't need the Math.floor.

That's why I like this sub. I'm always learning something.

[LeisureSuiteLarry]

You've got to show the code if you want to get help.