Using a class instead of struct.
#include <iostream> using namespace std; class MyClass { int i;// private by default public: int get_i(void); void put_i(int j); } ; int MyClass::get_i(void) { return i; } void MyClass::put_i(int j) { i = j; } main(void) { MyClass s; s.put_i(10); cout << s.get_i(); return 0; }