Nota parcial1 d'LTP

#include <iostream>
#include <string>
#include <conio.h>

using namespace std;

string toUpperCase(string);

int main()
{
    char chuleta [][20] =
        {
            {'B','A','A','C', 'C','C','C','B', 'D','A','D','A', 'D','D','B','B', 'B','C','B','C'},
            {'A','B','B','C', 'A','A','B','B', 'C','B','C','B', 'B','D','A','A', 'C','C','D','D'}
        };
    string auxR;
    enum examen {A, B, ERROR};
    int aux;

    cout << "Cual es tu examen?" << endl << "A -> 0" << endl << "B -> 1" << endl;
    cin >> aux;

    cout << endl << "Introduce tu respuesta, si no has contestado alguna pon una \'x\'" << endl << "Ejemplo: \"abxac\"" << endl;
    cin >> auxR;
    auxR = toUpperCase(auxR);

    double be=0.0,mal=0.0;
    for(int a=0;a<20;a++){
        if(auxR[a]==chuleta[aux][a]) be++;
        else if (auxR[a]!='X') mal++;
    }

    double aux2=0, nota=0.0;
    if (mal==0) aux2++; else aux2= mal/3;
    nota = be - aux2;
    nota = nota / 2.0;
    cout << endl << "Tu puntuacion es de " << nota << endl;

    getch();
}

string toUpperCase(string s){
    for (unsigned int a=0;a<s.length();a++)
    {
        if(s[a]>=((int)'a') && s[a]<=((int)'z'))
        {
            s[a]= (char)(((int)s[a])-32);
        }
    }

    return s;
}