How do I call the class's destructor?

Question

I have a simple C++ code, but I don\'t know how to use the destructor:

class date {

public:
    int day;
    date(int m)
    {
        day =m;
    }

    ~d         


        

Answer 1

Only in very specific circumstances you need to call the destructor directly. By default the destructor will be called by the system when you create a variable of automatic storage and it falls out of scope or when a an object dynamically allocated with new is destroyed with delete.

struct test {
   test( int value ) : value( value ) {}
   ~test() { std::cout << "~test: " << value << std::endl; }
   int value;
};
int main()
{
   test t(1);
   test *d = new t(2);
   delete d;           // prints: ~test: 2
}                      // prints: ~test: 1 (t falls out of scope)

For completeness, (this should not be used in general) the syntax to call the destructor is similar to a method. After the destructor is run, the memory is no longer an object of that type (should be handled as raw memory):

int main()
{
   test t( 1 );
   t.~test();            // prints: ~test: 1
                         // after this instruction 't' is no longer a 'test' object
   new (&t) test(2);     // recreate a new test object in place
}                        // test falls out of scope, prints: ~test: 2

Note: after calling the destructor on t, that memory location is no longer a test, that is the reason for recreation of the object by means of the placement new.