The standard streams have a boolalpha flag that determines what gets displayed -- when it's false, they'll display as 0 and 1. When it's true, they'll display as false and true.
There's also an std::boolalpha manipulator to set the flag, so this:
#include <iostream>
#include <iomanip>
int main() {
std::cout<<false<<"\n";
std::cout << std::boolalpha;
std::cout<<false<<"\n";
return 0;
}
...produces output like:
0
false
For what it's worth, the actual word produced when boolalpha is set to true is localized--that is, <locale> has a num_put category that handles numeric conversions, so if you imbue a stream with the right locale, it can/will print out true and false as they're represented in that locale. For example,
#include <iostream>
#include <iomanip>
#include <locale>
int main() {
std::cout.imbue(std::locale("fr"));
std::cout << false << "\n";
std::cout << std::boolalpha;
std::cout << false << "\n";
return 0;
}
...and at least in theory (assuming your compiler/standard library accept "fr" as an identifier for "French") it might print out faux instead of false. I should add, however, that real support for this is uneven at best--even the Dinkumware/Microsoft library (usually quite good in this respect) prints false for every language I've checked.
The names that get used are defined in a numpunct facet though, so if you really want them to print out correctly for particular language, you can create a numpunct facet to do that. For example, one that (I believe) is at least reasonably accurate for French would look like this:
#include <array>
#include <string>
#include <locale>
#include <ios>
#include <iostream>
class my_fr : public std::numpunct< char > {
protected:
char do_decimal_point() const { return ','; }
char do_thousands_sep() const { return '.'; }
std::string do_grouping() const { return "\3"; }
std::string do_truename() const { return "vrai"; }
std::string do_falsename() const { return "faux"; }
};
int main() {
std::cout.imbue(std::locale(std::locale(), new my_fr));
std::cout << false << "\n";
std::cout << std::boolalpha;
std::cout << false << "\n";
return 0;
}
And the result is (as you'd probably expect):
0
faux