I'm totally new to cpp but know some python. I want to create a class which has an array as an attribute with size given in the constructor. Here is what I want to do but in python:

```
class test:
    def __init__(self,size):
        self.arr = [x for x in range(size)]

```

This is what I have in c++:

```
class Field{
public:
    int width;
    int height;
    int field[];
    Field(int _width, int _height){
        width = _width;
        height = _height;
        field = new int[width*height];
    }
};

```

But when declaring the field I need to provide a size, but the size is only given later. How can I do this?