Who deletes the memory allocated during a “new” operation which has exception in constructor?

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You should refer to the similar questions here and here.
Basically if the constructor throws an exception you’re safe that the memory of the object itself is freed again. Although, if other memory has been claimed during the constructor, you’re on your own to have it freed before leaving the constructor with the exception.

For your question WHO deletes the memory the answer is the code behind the new-operator (which is generated by the compiler). If it recognizes an exception leaving the constructor it has to call all the destructors of the classes members (as those have already been constructed successfully prior calling the constructor code) and free their memory (could be done recursively together with destructor-calling, most probably by calling a proper delete on them) as well as free the memory allocated for this class itself. Then it has to rethrow the catched exception from the constructor to the caller of new.
Of course there may be more work which has to be done but I cannot pull out all the details from my head because they are up to each compiler’s implementation.

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