Demystifying C++ - New and Delete Operators
Demystifying C++ Article Series
In C++, the new operator is used to dynamically allocate memory and call the object's constructor, while the delete operator is used to call the destructor and subsequently free the memory. These operators significantly simplify memory management in C++ and reduce the likelihood of errors that often occur with manual memory management.
In the equivalent C code, memory is allocated or released via the global operator new and operator delete functions. The implementation of both functions is found in libc++ and uses malloc and free respectively.
| new | C1* obj = new C1(); |
struct C1* obj = (struct C1*)::operator new(sizeof(C1));
if (obj) {
C1_ctor_complete(obj);
}
|
|---|---|---|
| delete | delete obj; |
if (obj) {
C1_dtor_complete(obj);
::operator delete(obj);
}
|
The code generated by new/delete can become quite complex, for instance, when allocating or deallocating an array. In such cases, sometimes intricate loops for constructor and destructor handling are created.