#include <cstdlib>
#include <iostream>

using namespace std;

int main ( int argc, char *argv[] ) {
    float Iva, MontoFactura, Total, Euro, Dolar, Bs;
    double Con1, Con2, Con3;
    char s, n;
    string Moneda = {0};
    char   Exonerado = 0;

    system ( "color F6" );
    cout << "\t\t\t***Monto Total con IVA***\n\n";
    cout << "\n\n\n";
    cout << "\xA8"<<"El Producto esta Exonerado?";
    cout << "\n\n\n";
    cin >> Exonerado;
    
    if ( Exonerado == 's' || Exonerado == 'S' ) {
        cout << "Su producto esta excento del Iva";
    }
    else if ( Exonerado == 'n' || Exonerado == 'N' ) {
        cout << "\n\n\n";
        cout << "Ingrese el Monto de la Factura";
        cout << "\n\n\n";
        cin >> MontoFactura;
        cout << "Ingrese el tipo de moneda";
        cout << "\n\n\n";
        cin >> Moneda;
        
        if ( Moneda == "Euro" || Moneda == "euro" || Moneda == "E" || Moneda == "e" || Moneda == "EUR"|| Moneda == "eur" ) {
            Con1 = MontoFactura * 8.5636;
            cout << "Su monto en Bs es: " << Con1 << "";
            system ( "color F9" );
            Iva = Con1 * 0.12;
            cout << "\n\n\n";
            cout << "El Iva es: " << Iva << "";
            cout << "\n\n\n";
            Total = Iva + Con1;
            cout << "El Total con iva es de: " << Total << "";
            cout << "\n\n\n";
        }
        
        if ( Moneda == "Dolar"|| Moneda == "dolar" || Moneda == "D" || Moneda == "d" || Moneda == "$"  ) {
            Con2 = MontoFactura * 6.3000;
            cout << "XXXSu monto en Bs es: " << Con2 << "";
            system ( "color F9" );
            Iva = Con2 * 0.12;
            cout << "\n\n\n";
            cout << "El Iva es: " << Iva << "";
            cout << "\n\n\n";
            Total = Iva + Con2;
            cout << "El Total con iva es de: " << Total << "";
            cout << "\n\n\n";
        }
        
        if ( Moneda == "Bs" ) {
        
            Con3 = MontoFactura;
            system ( "color F9" );
            Iva = Con3 * 0.12;
            cout << "\n\n\n";
            cout << "El Iva es: " << Iva << "";
            cout << "\n\n\n";
            Total = Iva + Con3;
            cout << "El Total con iva es de: " << Total << "";
            cout << "\n\n\n";
        }
    }
    
    system ( "PAUSE" );
    return EXIT_SUCCESS;
}

std::logic_error: basic_string::_S_construct NULL not valid
Aborted.