Compare iterators, C++

Question

Is it possible to compare two iterators? A comparision using std::min

void change ( typename TList <Item *>::Type ::iterator it_begin, typename TList <Item*>::Type ::iterator it_end )
{
   ....
this->items.resize ( index );
   std::sort ( it_begin, std::min (it_end, it_begin += index - 1); //Compare two iterators, exception
....
}

throws the following exception:

Assertion failed: Vector iterators  incompatible... 

Is there any other way of the comparision?

Answer 1

Yes. But I doubt if you can do that with std::min.

You can use std::distance function to calculate the distance between two iterators. And then you can use the distance to determine which iterator is the smaller one. Once you know the smaller iterator, you can pass that to std::sort function.

Here is small illustration how to calculate distance:

#include <iostream>
#include <iterator>
#include <vector>

int main() {
    std::vector<int> v(100); //vector of size 100
    std::cout <<(std::distance(v.begin(), v.begin() + 10))<< std::endl;
    std::cout <<(std::distance(v.begin() +25, v.begin() +10))<< std::endl;
}

Output:

10
-15

Hope that gives you enough idea how to proceed to do what you want to.