In C + +:: operator new,:: operator delete

In general, when using new and delete, two things are done, one is the configuration of the space (new is the allocation, the delete is the recycle), but the destructor of the calling object

But there are ways to separate the two processes.

That is explicit invocation:: operator new,:: operator delete, they are only spatially configured, do not call the object's destructor

See the following example for details:

//Operator new[] Example#include <iostream>//Std::cout#include <new>//:: operator new[]structMyClass {intData MyClass () {std::cout <<‘*‘;}//Print an asterisk for each construction};intMain () {std::cout <<"constructions (1): ";//Allocates and constructs five objects:MyClass * P1 =newMYCLASS[5]; Std::cout <<‘\n‘; Std::cout <<"constructions (2): ";//Allocates and constructs five objects (nothrow):MyClass * P2 =new(Std::nothrow) MYCLASS[5]; Std::cout <<‘\n‘; Std::cout <<"constructions (3): ";//Allocates storage for five objects, but does not construct them:MyClass * P3 =static_cast<MyClass*> (::operator new(sizeof(Myclass[5])); Std::cout <<‘\n‘; Std::cout <<"constructions (4): ";//Constructs five objects at P3, but does not allocate: new(p3) MYCLASS[5]; Std::cout <<‘\n‘;delete[] P3;delete[] P2;delete[] P1;return0;}

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For operator delete and operator new, you can see the prototype definition here:

Http://en.cppreference.com/w/cpp/memory/new/operator_delete

Http://en.cppreference.com/w/cpp/memory/new/operator_new

As you can see, they are all void*-type pointers, almost like the malloc free mechanism in the C language.

In C + +:: operator new,:: operator delete