{

// We can achieve this at the function call site

// with the previously defined policy C_error_policy.

double t = tgamma(4., C_error_policy());

cout << "tgamma(4., C_error_policy() = " << t << endl; // 6

// Alternatively we could use the function make_policy,

// provided for convenience,

// and define everything at the call site:

t = tgamma(4., make_policy(

domain_error<errno_on_error>(),

pole_error<errno_on_error>(),

overflow_error<errno_on_error>(),

evaluation_error<errno_on_error>()

));

cout << "tgamma(4., make_policy(...) = " << t << endl; // 6

return 0;