コード例 #1
0
int main(void) {

    // const MyClass1 mine1; // fails to compile: we haven't defined a constructor without arguments
    const MyClass1 mine1a=2;
    const MyClass1 mine1b(2);
    MyClass1 mine1c(2);
    // int q1=mine1a.cc;// fails to compile: cc is a clandestine member of MyClass1, we don't need to know about it
    int q2=mine1a.getvalue(); // ok
    int q3=mine1b.getvalue(); // ok
    // int q4=mine1a.getvalue_nonconst(); // fails to compile: mine1a is a const object, and the compiler has no way
    //                                       to know that the function getvalue_nonconst() is not modifying it, so,
    //                                       like an over-cautious parent it throws a compile error, keeping us safe.
    int q5=mine1c.getvalue_nonconst(); // ok

    std::cout << "cc for 'const MyClass1 mine1a=2'  : " << q2 << std::endl;
    std::cout << "cc for 'const MyClass1 mine1b(2)' : " << q3 << std::endl;
    std::cout << "cc for 'MyClass1 mine1c(2)'       : " << q5 << std::endl;

    return EXIT_SUCCESS;
}
コード例 #2
0
int main(void) {
  // We can't use the default constructor on MyClass1 because the constructor
  // needs to initialize the const member variable cc.
  // const MyClass1 mine1; // fails to compile 
  const MyClass1 mine1a=2;
  const MyClass1 mine1b(2);
  MyClass1 mine1c(2);
  // mine1a.cc is private.
  // int q1=mine1a.cc;// fails to compile
  int q2=mine1a.getvalue(); // ok
  int q3=mine1b.getvalue(); // ok
  // You can't call a non-const member function of a const instance, because
  // it might modify the instance.
  // int q4=mine1a.getvalue_nonconst(); // fails to compile
  int q5=mine1c.getvalue_nonconst(); // ok
  
  std::cout << "cc for 'const MyClass1 mine1a=2'  : " << q2 << std::endl;
  std::cout << "cc for 'const MyClass1 mine1b(2)' : " << q3 << std::endl;
  std::cout << "cc for 'MyClass1 mine1c(2)'       : " << q5 << std::endl;
  
  return EXIT_SUCCESS;
}