What happens to the memory allocated by `new` if the constructor throws?

Question

Will this code cause a memory leak?

#include <stdexept>  class MyClass { public:     MyClass()     {         throw std::runtime_error("Test");     } };  int main() {     try     {         MyClass * myClass = new MyClass;     }     catch (const std::exception & exc)     {         // Memory leak?     }     return 0; } 

The memory allocated by new is never deleted. Is this taken care of internally, or it an actual memory leak?

Answer 1

The memory will be automatically freed before the exception propagates.

This is essential, because a) the program never receives a pointer to free, and b) even if it did, it would have no portable way to actually free it since the memory never became an object that you can delete.

Answer 2

The memory will be properly deallocated.

Related questions at SO.

Is it ever not safe to throw an exception in a constructor?

C++ : handle resources if constructors may throw exceptions (Reference to FAQ 17.4)

prasoon@prasoon-desktop ~ $ cat noleak.cpp && g++ noleak.cpp && valgrind --leak-check=full ./a.out #include <stdexcept>  class MyClass { public:     MyClass()     {         throw std::runtime_error("Test");     } };  int main() {     try     {         MyClass * myClass = new MyClass;     }     catch (const std::exception & exc)     {         // Memory leak?     }     return 0; } ==3652== Memcheck, a memory error detector ==3652== Copyright (C) 2002-2009, and GNU GPL'd, by Julian Seward et al. ==3652== Using Valgrind-3.5.0 and LibVEX; rerun with -h for copyright info ==3652== Command: ./a.out ==3652==  ==3652==  ==3652== HEAP SUMMARY: ==3652==     in use at exit: 0 bytes in 0 blocks ==3652==   total heap usage: 3 allocs, 3 frees, 106 bytes allocated ==3652==  ==3652== All heap blocks were freed -- no leaks are possible ==3652==  ==3652== For counts of detected and suppressed errors, rerun with: -v ==3652== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 17 from 6) prasoon@prasoon-desktop ~ $