Does C++ support 'finally' blocks? (And what's this 'RAII' I keep hearing about?)

Question

Does C++ support \'finally\' blocks?

What is the RAII idiom?

What is the difference between C++\'s RAII idiom and C#\'s \'using\' statement?

Answer 1

Not really, but you can emulate them to some extend, for example:

int * array = new int[10000000];
try {
  // Some code that can throw exceptions
  // ...
  throw std::exception();
  // ...
} catch (...) {
  // The finally-block (if an exception is thrown)
  delete[] array;
  // re-throw the exception.
  throw; 
}
// The finally-block (if no exception was thrown)
delete[] array;

Note that the finally-block might itself throw an exception before the original exception is re-thrown, thereby discarding the original exception. This is the exact same behavior as in a Java finally-block. Also, you cannot use return inside the try&catch blocks.