std::iter_swap

#include <algorithm>
#include <iostream>
#include <random>
#include <string_view>
#include <vector>
 
template<class ForwardIt>
void selection_sort(ForwardIt begin, ForwardIt end)
{
 for (ForwardIt it = begin; it != end; ++it)
 std::iter_swap(it, std::min_element (it, end));
}
 
void println(std::string_view rem, std::vector <int> const& v)
{
 std::cout << rem;
 for (int e : v)
 std::cout << e << ' ';
 std::cout << '\n';
}
 
template<int min, int max>
int rand_int()
{
 static std::uniform_int_distribution dist(min, max);
 static std::mt19937 gen(std::random_device {}());
 return dist(gen);
}
 
int main()
{
 std::vector <int> v;
 std::generate_n (std::back_inserter (v), 20, rand_int<-9, +9>);
 
 std::cout << std::showpos ;
 println("Before sort: ", v);
 selection_sort(v.begin(), v.end());
 println("After sort: ", v);
}

Before sort: -9 -3 +2 -8 +0 -1 +8 -4 -5 +1 -4 -5 +4 -9 -8 -6 -6 +8 -4 -6 
After sort: -9 -9 -8 -8 -6 -6 -6 -5 -5 -4 -4 -4 -3 -1 +0 +1 +2 +4 +8 +8