C++ Cookbook

13.4. Writing and Reading Currency

Problem

You need to write or read a formatted currency value to or from a stream.

Solution

Use the money_put and money_get facets to write and read currency, as shown in Example 13-6.

Example 13-6. Writing and reading currency

#include <iostream> #include <locale> #include <string> #include <sstream> using namespace std; long double readMoney(istream& in, bool intl = false) { long double val; // Create a reader facet const money_get<char>& moneyReader = use_facet<money_get<char> >(in.getloc()); // End marker istreambuf_iterator<char> end; // State variable for detecting errors ios_base::iostate state = 0; moneyReader.get(in, end, intl, in, state, val); // failbit will be set if something went wrong if (state != 0 && !(state & ios_base::eofbit)) throw "Couldn't read money!\n"; return(val); } void writeMoney(ostream& out, long double val, bool intl = false) { // Create a writer facet const money_put<char>& moneyWriter = use_facet<money_put<char> >(out.getloc()); // Write to the stream. Call failed() (the return value is an // ostreambuf_iterator) to see if anything went wrong. if (moneyWriter.put(out, intl, out, out.fill(), val).failed()) throw "Couldn't write money!\n"; } int main() { long double val = 0; float exchangeRate = 0.775434f; // Dollars to Euros locale locEn("english"); locale locFr("french"); cout << "Dollars: "; cin.imbue(locEn); val = readMoney(cin, false); cout.imbue(locFr); // Set the showbase flag so the currency char is printed ...