C++, is it possible to call a constructor directly, without new?

Question

Can I call constructor explicitly, without using new, if I already have a memory for object?

class Object1{
    char *str;
public:
    Object1(c         


        

Answer 1

Sort of. You can use placement new to run the constructor using already-allocated memory:

 #include 

 Object1 ooo[2] = {Object1("I'm the first object"), Object1("I'm the 2nd")};
 do_smth_useful(ooo);
 ooo[0].~Object1(); // call destructor

 new (&ooo[0]) Object1("I'm the 3rd object in place of first");

So, you're still using the new keyword, but no memory allocation takes place.