新向量的向量

Question

Suppose I have a vector of dynamically allocated vectors, something like:

std::vector<std::vector<double>*> map;

Do i have to deallocate each of the vectors inside map manually or are they deallocated automatically by the vector destructor itself? If I have to do it manually is this a good way to go:

for(auto& t : map) delete[] t;

?

Answer 1

You would need to free them with delete not delete [] because a vector is not an array.

But I wouldn't see any reason why you wouldn't use

std::vector<std::vector<double>>

This way you wouldn't need to worry about the allocation of the vector

Answer 2

Do i have to deallocate each of the vectors inside map manually or are they deallocated automatically

If you allocate manually, then you must deallocate manually (unless you transfer ownership to a smart pointer in which case you preferably should not have allocated manually in the first place).

Allocating vectors manually is not a good way.