Performing Currency Exchanges
The following code shows how exchange rates and tables, exchange objects and groups, and the exchange factory come together to perform a currency exchange. The comments in the code detail each part of the program.
#include <rw/currency/money.h>
#include <rw/currency/euroexchggrp.h>
#include <rw/currency/divexchggrp.h>
#include <rw/currency/exchgfact.h>
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// Create and initialize an exchange rate table
// to be used for all currency conversions.
RWExchangeRateTable rateTable;
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// Create an exchange factory that uses the exchange rate
// table created above. By default the exchange factory contains
// the multiplication exchange group.
RWExchangeFactory<double> exchangeFactory( rateTable );
// Add a Euro exchange group
ifstream euroCurrenciesFile( "euro_currencies.txt" );
RWExchangeGroup<double> euroGroup =
RWEuroGroup<double>::create( euroCurrenciesFile );
exchangeFactory.appendExchangeGroup( euroGroup );
// Add a division exchange group
RWExchangeGroup<double> divGroup =
RWDivisionGroup<double>::create();
exchangeFactory.appendExchangeGroup( divGroup );
// The exchange factory contains three exchange groups:
// RWMultiplicationGroup, RWEuroGroup, and RWDivisionGroup,
// in that order.
// Get an exchange object from the factory for converting Belgian
// Francs to Canadian Dollars. Since the factory's exchange rate
// table contains a conversion factor for converting Belgian Francs
// to Canadian Dollars, it creates an exchange object containing
// an RWMultiplicationExchange implementation. Exchanges are
// computed by multiplying the source amount by the conversion
// conversion factor.
RWExchange<double> befToCadExchanger =
exchangeFactory.getExchange( "BEF", "CAD" );
// Get an exchange object from the factory for converting Belgian
// Francs to French Francs. The factory's exchange rate table does
// not contain a conversion factor for converting Belgian Francs to
// French Francs. Belgium and France are members of the EMU, so
// instead, the exchange rate table contains conversion factors for
// converting Euros to Belgian Francs and Euros to French Francs.
// This means that the Factory creates an RWExchange object with an
// RWTriangularExchange implementation.
RWExchange<double> befToFrfExchanger =
exchangeFactory.getExchange( "BEF", "FRF" );
// Get an exchange object from the factory for converting Belgian
// Francs to Euros. The factory's exchange rate table does not
// contain a conversion factor for converting Belgian Francs to
// Euros and the Euro is not a local Euro currency. There is,
// however, a conversion factor for converting Euros to Belgian
// Francs in the factory's exchange rate table. Thus the last
// exchange group in the list, RWDivisionGroup, creates an exchange
// object with an RWDivisionExchange implementation.
RWExchange<double> befToEURExchanger =
exchangeFactory.getExchange( "BEF", "EUR" );
// Do the exchanges, using the exchange function of each exchange object.
RWMoney<double> moneyBEF( 189972.76, "BEF" );
if ( befToCadExchanger.isValid() )
{
RWMoney<double> moneyCAD = befToCadExchanger.exchange(moneyBEF);
}
if ( befToFrfExchanger.isValid() )
{
RWMoney<double> moneyFRF = befToFrfExchanger.exchange(moneyBEF);
}
if ( befToEURExchanger.isValid() )
{
RWMoney<double> moneyEUR = befToEURExchanger.exchange(moneyBEF);
}