CODEWITHSUNDEEP
c++qtvectorc++98
MistyD
MistyD

Reputation: 17223

Can you pass pointers to iterators of a std::vector

I came across the following code and it raised some questions in my head

std::vector<unsigned char> buf(bytes.constData(), bytes.constData() + bytes.size());

where bytes is QByteArray and bytes.constData() returns const char*

I went over the constructor of the vector here and the only constructor that I think fits for this description is

 vector (InputIterator first, InputIterator last,
                 const allocator_type& alloc = allocator_type());

Now my question is:

1-Is it possible to pass a pointer to an iterator of a vector ? and why is it bytes.constData() + bytes.size() ? Does this make a copy for instance if we later made changes to bytes would it affect buf ?

Upvotes: 0

Views: 281

Answers (1)

Kerrek SB
Kerrek SB

Reputation: 476970

"An iterator of a vector" is misguided here: the vector constructor in question is a template and accepts any iterator. That's the whole point -- you can construct the container from any iterable range.

And pointers are indeed iterators. In fact, the entire concept of iterators is basically a generalization of the notion of a "pointer".

The vector constructor copies the data from the input range, so later changes to bytes will not affect the vector.

Upvotes: 4

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