#include < iostream > #include < string > using namespace std; class person { public: person(const string n, int a, const unsigned long ss) :name(n), age(a), soc_sec(ss){} void bday() const {++age;} //had been non-const void print() const { cout << name << " is " << age << " years old with SSN " << soc_sec << endl; } private: const string name; mutable int age; const unsigned long soc_sec; }; int main() { const person ira("ira pohl", 38, 1110111UL); ira.print(); ira.bday(); ira.print(); }