Menu
Guys, I have a midterm examination tomorrow, and I was looking over the sample paper, and I'm not sure about this question. Any help would be appreciated.
Let v be a vector<Thingie*>, so that each element v[i] contains a pointer to a Thingie. If p is a vector<Thingie*>::iterator, answer the following questions:
p?*p?Thingie?Thingie?
590
An iterator is an object (like a pointer) that points to an element inside the container. We can use iterators to move through the contents of the container. They can be visualized as something similar to a pointer pointing to some location and we can access the content at that particular location using them.
Vector's iterators are random access iterators which means they look and feel like plain pointers. You can access the nth element by adding n to the iterator returned from the container's begin() method, or you can use operator [] .
You can store pointers in a vector just like you would anything else. Declare a vector of pointers like this: vector<MyClass*> vec; The important thing to remember is that a vector stores values without regard for what those values represent.
A pointer of type T* can point to any type T object. An iterator is more restricted, e.g., a vector::iterator can only refer to doubles that are inside a vector container.
what type is
p?
p is of type vector<Thingie*>::iterator, whatever type that happens to be.
what type is
*p?
*p is a Thingie*&; that is, it is a reference to the element in the vector at which the iterator points.
what code provides the address of the actual
Thingie?
*p, since the elements of the vector are pointers to the Thingies, and *p gives a reference to the element in the vector.
what code provides the actual
Thingie?
**p; that is, you dereference the pointer obtained by *p to obtain the referent of the pointer.
135
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With
