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// error_code::assign
#include <iostream> // std::cout
#include <cerrno> // errno
#include <system_error> // std::error_code, std::generic_category
#include <cmath> // std::pow
struct expnumber {
double value;
std::error_code error;
expnumber (double base, double exponent) {
value = std::pow(base,exponent);
if (errno) error.assign (errno,std::generic_category());
}
};
int main()
{
expnumber foo (3.0, 2.0);
std::cout << foo.value << "\t" << foo.error.message() << '\n';
expnumber bar (3.0, 10e6);
std::cout << bar.value << "\t" << bar.error.message() << '\n';
return 0;
}