In your example that you provided str will not be destructed. The standard states in [class.union]/2 A union can have member functions (including constructors and destructors), but not virtual (10.3) functions. A union shall not have base classes. A union shall not be used as a base class. If a union contains a non-static data … Read more
Wikipedia has some good discussion on the difference between a finalizer and a destructor in the finalizer article. C# really doesn’t have a “true” destructor. The syntax resembles a C++ destructor, but it really is a finalizer. You wrote it correctly in the first part of your example: ~ClassName() { } The above is syntactic … Read more
It happens because you told it to happen. The destructor for an automatic variable is always called when the variable goes out of scope. You also called it. That’s two calls total. Calling an object’s destructor does not signal to C++ not to call it again, since in normal execution there is no need to … Read more
A virtual destructor is only useful for inheritance scenarios. STL containers are not designed to be inherited from (nor is it a supported scenario). Hence they don’t have virtual destructors.
It’s the reason that makes your code work for generic parameters. Consider a container C: template<typename T> struct C { // … ~C() { for(size_t i = 0; i<elements; i++) buffer[i].~T(); } }; It would be annoying to introduce special cases for built-in types. So C++ allows you to do the above, even if T … Read more
The destructor of A will run when its lifetime is over. If you want its memory to be freed and the destructor run, you have to delete it if it was allocated on the heap. If it was allocated on the stack this happens automatically (i.e. when it goes out of scope; see RAII). If … Read more
Yes, there will be adverse effects. You must not delete an object that was not allocated with new. If the object was allocated on the stack, your compiler has already generated a call to its destructor at the end of its scope. This means you will call the destructor twice, with potentially very bad effects. … Read more
It’s explicitly legal. The rule is that the types used to instantiate a template in the standard library must be complete, unless otherwise specified. In the case of unique_ptr, §20.7.1/5 says “[…] The template parameter T of unique_ptr may be an incomplete type.” There are certain operations on the pointer which require a complete type; … Read more
The __destruct will not be called: If exit is called in another destructor Depending on the PHP Version: if exit is called in a shutdown function registered with register_shutdown_function If there is a fatal error somewhere in the code If another destructor throws an exception If you try to handle an exception in a destructor … Read more
Yes, removing a Foo* from a container destroys the Foo*, but it will not release the Foo. Destroying a raw pointer is always a no-op. It cannot be any other way! Let me give you several reasons why. Storage class Deleting a pointer only makes sense if the pointee was actually allocated dynamically, but how … Read more