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reading character array and translating

sierranm (76)
So I'm trying to make this code work, and so far the code I have, no matter what I enter I receive my debug error code: Error: Invalid characters encountered

This happens even when it is an m, d, x, v, i, l, etc. What am I doing wrong?

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#include <iostream>
#include <string>
#include <fstream>
using namespace std;



int main()
{
	char num[10];
	int sum = 0, i = 0;
	cout << "Enter a Roman numeral: "; //decide on a limit? Or an equation that should work it all out?
	cin >> num[5];
	for (int i = 0; i < 10; i++)//Sum
	{
		num[i] = tolower(num[i]);
		switch (num[i])
		{
		case 'm': sum += 1000; break;
		case 'd': sum += 500; break;
		case 'c': sum += 100; break;
		case 'l': sum += 50; break;
		case 'x': sum += 10; break;
		case 'v': sum += 5; break;
		case 'i':
			if (num[i + 1] == 'v')
			{
				sum -= 1;
			}
			else if (num[i + 1] == 'x')
			{
				sum -= 1;
			}
			else if (num[i + 1] == 'l')
			{
				sum -= 1;
			}
			else if (num[i + 1] == 'd')
			{
				sum -= 1;
			}
			else if (num[i + 1] == 'c')
			{
				sum -= 1;
			}
			else if (num[i + 1] == 'm')
			{
				sum -= 1;
			}
			else if (num[i + 1] == 'i')
			{
				sum += 1;
			}
			else if (num[i - 1] == 'i')
			{
				sum += 1;
			}
			else if (num[i - 1] == 'v')
			{
				sum += 1;
			}
			else if (num[i - 1] == 'x')
			{
				sum += 1;
			}
			else if (num[i - 1] == 'c')
			{
				sum += 1;
			}
			else if (num[i - 1] == 'm')
			{
				sum += 1;
			}
			else if (num[i - 1] == 'd')
			{
				sum += 1;
			}
			else if (num[i - 1] == 'l')
			{
				sum += 1;
			}
			break;
		default:
			cout << "Error: Invalid characters encountered." << endl;
			int error = 1;
			sum = 0;
			while (error != 0)
			{
				cout << "Enter a roman numeral:\t";
				cin >> num;
				for (int i = 0; i < 5; i++)//Sum
				{
					num[i] = tolower(num[i]);
					switch (num[i])
					{
					case 'm': sum += 1000; break;
					case 'd': sum += 500; break;
					case 'c': sum += 100; break;
					case 'l': sum += 50; break;
					case 'x': sum += 10; break;
					case 'v': sum += 5; break;
					case 'i':
						if (num[i + 1] == 'v')
						{
							sum -= 1;
						}
						else if (num[i + 1] == 'x')
						{
							sum -= 1;
						}
						else if (num[i + 1] == 'l')
						{
							sum -= 1;
						}
						else if (num[i + 1] == 'd')
						{
							sum -= 1;
						}
						else if (num[i + 1] == 'c')
						{
							sum -= 1;
						}
						else if (num[i + 1] == 'm')
						{
							sum -= 1;
						}
						else if (num[i + 1] == 'i')
						{
							sum += 1;
						}
						else if (num[i - 1] == 'i')
						{
							sum += 1;
						}
						else if (num[i - 1] == 'v')
						{
							sum += 1;
						}
						else if (num[i - 1] == 'x')
						{
							sum += 1;
						}
						else if (num[i - 1] == 'c')
						{
							sum += 1;
						}
						else if (num[i - 1] == 'm')
						{
							sum += 1;
						}
						else if (num[i - 1] == 'd')
						{
							sum += 1;
						}
						else if (num[i - 1] == 'l')
						{
							sum += 1;
						}
						break;
					default:
						cout << "Error: Invalid characters encountered." << endl;
						int error = 1;
						sum = 0;
					}//end switch
				}//end for
			}//end while
		}//end for
	}//end while
	cout << endl;
	cout << "The Roman numeral, " << num << " translates to Arabic number, " << sum << "." << endl;
	return 0;
}
Last edited on
keskiverto (10402)
Please explain line 13.
sierranm (76)
Oops! I changed the number of characters from 5 to 10. Forgot to change that one...I'm not actually even sure if I can just say

cin >> num;

of if it has to be num[10];
cire (8284)
Since num is an array of char, num[index] is a single char. So, when you do cin >> num[index] regardless of what index is, you are asking for a single character to be extracted from cin.

Valid indexes for an array if size x are 0 to x-1. If you were to write cin >> num[10]; and num only contained 10 elements, you would be accessing an element of num that did not exist.

I would recommend the use of cin.getline here.
Last edited on
sierranm (76)
Okay, so I changed it to the getline, but getline has a squiggly line beneath it. Any ideas? 

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char num[10];
		int sum = 0, i = 0;
		cout << "Enter a Roman numeral: "; //decide on a limit? Or an equation that should work it all out?
		getline(cin, num[]);
		for (int i = 0; i < 10; i++)//Sum
		{
			num[i] = tolower(num[i]);
			switch (num[i])
cire (8284)
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    const unsigned num_size = 10 ;
    char num[num_size];
    cout << "Enter a Roman numeral: ";
    cin.getline(num, num_size);
    ...

Last edited on
keskiverto (10402)
The line 2 of the first code:
#include <string>

Lets make a use for it.
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string num;
cout << "Enter a Roman numeral: ";
cin >> num;
for ( size_t i = 0; i < num.size(); ++i )
{
  num[i] = tolower(num[i]);
  switch (num[i])
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