Re: getting a slice off a vector
On 9/19/2011 8:13 AM, persres@googlemail.com wrote:
Hello,
I want to take subsequence from a vector and store it in a
different vector. I would like to avoid copying. Is there something
available in boost or stl.
Say,
vector<int> v(0,1,2,3,4,5,6,7,8,9,10);
I want vector<int> slice to hold 5,6,7,8.
I should be able to do:
Is there a wrapper class like this -
template<class T>
struct SliceOfVector
{
SliceOfVector(pair< vector<T>::iterator , vector<T>::iterator
) ;
pair< vector<T>::iterator , vector<T>::iterator> m_range;
vector<T>& m_original;
};
SliceOfVector should have all semantics same as vector. May be even
derives from vector<T>.
I should be able to treat SliceOfVector just like a vector, just that
it would be the subsequence specified by m_range of the original
vector.
Am I making sense. Please let me know if you have any suggestions.
Storing iterators is dangerous. Storing std::vector iterators is
dangerous squared. Basically you need to make sure that your vector
does not reallocate its memory because that action invalidates all
iterators, pointers and references to vector's elements.
I recommend storing indices. In the debug version of your program I'd
actually check against the size of 'm_original' every time the vector is
accessed using the index.
V
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