Iterators

// Iterators.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"
#include <vector>
#include <algorithm>
#include <numeric>
#include <iterator>
#include <deque>
#include <array>

using namespace std;


int main()
{
    vector<int> v1(10); //Create a vector and give the value of 10
    fill(begin(v1), end(v1), 1); //Fill the vector with the value of 1
    fill_n(begin(v1), 6, 2); //Fill the six first values with value of two
    iota(begin(v1), end(v1), 1);//Iota makes count till 10

    vector<int> v2;//Create the vector
    fill_n(back_inserter(v2), 6, 2);//Put the size of six on this vector and fill with the value of two
    generate_n(back_inserter(v2), 10, [n = 0]()mutable{return n++; });//Increase the size of Vector to put values from 0 till 10

    //Vector dont support fron inserter but deque support, to use front_inserter we create a deque<int> besides a vecor<int>
    deque<int> q3;
    fill_n(front_inserter(q3), 6, 2);
    generate_n(front_inserter(q3), 10, [n = 0]()mutable{return n++; });

    //fill_n(front_inserter(v1), 6, 2); //you cant use front_inserter on vector

    v2.clear(); //Clean the values inside vector
    transform(begin(v1), end(v1), back_inserter(v2),
        [](int elem) {return elem * 2; }); //Pick up every element on v1 and put on v2 AND the lambda double every value to put on v2

    vector<int> v3{ 3, 6, 1, 0, -2, 5 };
    vector<int> v5;
    copy_if(begin(v3), end(v3), back_inserter(v5),
        [](int elem) {return elem % 2 == 0; }); //The lambda return true for even numbers and false for odd numbers

    v3[3] = -2;
    vector<int> v6;
    unique_copy(begin(v3), end(v3), back_inserter(v6));

    string sentence = "Hello, world!";
    string reverse;
    reverse_copy(begin(sentence), end(sentence), back_inserter(reverse));

    //At this point v1 has values from 0,1 till 10
    v2.clear();//v2 is now empty
    copy(rbegin(v1), rend(v1), back_inserter(v2)); //Insert values from v1 to v2 in reverse order

    v1[5] = 2; //Change an expecific element

    //Using front interator (begin) (end)
    auto two = find(begin(v1), end(v1), 2); //points to value of 2 on the list v1
    auto distance = two - begin(v1); //Calculate the distance from the value searched from the beginning of the list
    two++;//Increments

    //Using reverse interator (rbegin) (rend)
    auto rtwo = find(rbegin(v1), rend(v1), 2);
    distance = rtwo - rbegin(v1);
    rtwo++;

    //distance = rtwo - two; //It will give error because they are different operators

    //is "3" in the first or second half?
    auto three = find(begin(v1), end(v1), 3);
    bool firsthalf = (three - begin(v1) < end(v1) - three);
    //What about "9" ?
    auto nine = find(begin(v1), end(v1), 9);
    firsthalf = (nine - begin(v1) < end(v1) - nine);

    array<const int, 5> ca = { 3,1,6,0,2 };
    auto it = begin(ca);
    it++;
    //*it = 7;
    int i = *it; //Run till second value of the array and points to it

    //vector<const int> vc;

    it = find(begin(ca), end(ca), 1);
    it++; //Now the int i above still with the value with gets previously but the it pointer is now 6
    //*it = 7;
    //it = cbegin(ca);

    auto it2 = begin(v2);
    it2++;
    *it2 = 7;

    auto cit = cbegin(v2);
    cit++;
    //*cit = 7;


    return 0;
}