When malloc() fails, it will return a null pointer. But… What about new? It throws an exception… correct! But… What about the pointer? Any pointers returned?
See following code:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 | // Author Name: Need-Being // Modification date: 22/03/2012 // File description: Sample code to show what happens when throw exception in // constructor. #include <iostream> using namespace std; class Object { public: Object() { cout << "Object: Constructor called" << endl; } ~Object() { cout << "Object: Destructor called" << endl; } }; class Test { public: Test() { cout << "Test: Constructor called" << endl; throw 0; // Throw a exception by force } ~Test() { cout << "Test: Destructor called" << endl; } private: Object object; }; int main() { Test* test = (Test*)1; printf("Test pointer: %p\n", test); try { test = new Test(); } catch (...) { cout << "Exception caught" << endl; } printf("Test pointer: %p\n", test); return 0; } |
Running result:
Test pointer: 0x1
Object: Constructor called
Test: Constructor called
Object: Destructor called
Exception caught
Test pointer: 0x1
In this case you can find out that the Test instance is freed without calling its destructor. Also, the value of test is not changed.
