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(char*str1){         str=strdup(str1);         puts("ctor");         puts(str);     }     ~Object1(){         puts("dtor");         puts(str);         free(str);     } };  Object1 ooo[2] = {      Object1("I'm the first object"), Object1("I'm the 2nd") };  do_smth_useful(ooo); ooo[0].~Object1(); // call destructor ooo[0].Object1("I'm the 3rd object in place of first"); // ???? - reuse memory 

Answer 1

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

 #include <new>   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.