Slicing a vector

Question

I have a std::vector. I want to create iterators representing a slice of that vector. How do I do it? In pseudo C++:

class InterestingType;

void doSomethi         


        

Answer 1

use boost range adapters. they are lazy:

operator|() is used to add new behaviour lazily and never modifies its left argument.

boost::for_each(v|sliced(1,5)|transformed(doSomething));

doSomething needs to take range as input. a simple (may be lambda) wrapper would fix that.

Answer 2

Taken from here:

std::vector<myvector::value_type>(myvector.begin()+start, myvector.begin()+end).swap(myvector);

Usage example:

#include <iostream>
#include <vector>

int main ()
{
    std::vector<int> indexes{3, 6, 9};

    for( auto index : indexes )
    {
        int slice = 3;
        std::vector<int> bar{1, 2, 3, 4, 5, 6, 7, 8, 9};
        std::vector<int>( bar.begin() + index - slice, bar.begin() + index ).swap(bar);

        std::cout << "bar index " << index << " contains:";
        for (unsigned i=0; i<bar.size(); i++)
            std::cout << ' ' << bar[i];
        std::cout << '\n';
    }

    return 0;
}

Outputs:

bar index 3 contains: 1 2 3
bar index 6 contains: 4 5 6
bar index 9 contains: 7 8 9