From here http://www.cplusplus.com/reference/new/operator%20new[]/, it is unclear to me is it possible to allocate and construct objects with parameters. Like this:
struct MyClass {
int data;
MyClass(int k) {}
};
int main () {
// allocates and constructs five objects:
MyClass * p1 = new MyClass[5](1); // allocate 5 objects, and init all with '1'
}
Which is not work...
That wouldn't work, but you can use an std::vector<MyClass> for that:
std::vector<MyClass> p1(5, 1);
This will create a vector containing 5 MyClass objects. Note that this works because your single parameter constructor is not explicit. If it were, you would need
std::vector<MyClass> p1(5, MyClass(1));
MyClass * p3 = static_cast<MyClass*> (::operator new (sizeof(MyClass[5]))); And than call constructor explicitly for each object?What you wrote does not work, but you could do this since C++11.
Still, better avoid dynamic allocation and go for automatic object.
Also, most times you really should use a standard container like std::array or std::vector.
MyClass * a = new MyClass[5]{1,1,1,1,1};
MyClass b[5] = {1,1,1,1,1};
std::vector<MyClass> c(5, 1);
std::vector<MyClass> d(5, MyClass(1));
std::array<MyClass,5> e{1,1,1,1,1};
