Cherno Iterator Basics

#include <iostream>
#include <vector>
#include <unordered_map> // Essentially a hash map, doesn't store variables in any order

int main()
{
    std::vector<int> values = { 1, 2, 3, 4, 5 };

    for (int i = 0; i < values.size(); i++)
    {
        std::cout << values[i] << std::endl;
    }

    for (int value : values) // range-based for loop c++11
    {
        // value is the name of the current element we're iterating over while values is the whole collection
        std::cout << value << std::endl;
    }

    // Will run as long as iterator isn't equal to the end of this collection
    // Why use this over a range-based for loop since the other is shorthand? You wouldn't aside from wanting to manipulate position of iterator.
    // Certain situations where you would want this: A) erasing an element but continue to iterate over the rest of the collection
    // B) Insert something into the middle based on a condition
    for (std::vector<int>::iterator it = values.begin(); // Normal iterator
        it != values.end(); it++)
    {
        std::cout << *it << std::endl;
    }

    // Cherno doesn't use using with iterators, only with the type sometimes
    using ScoreMap = std::unordered_map<std::string, int>;
    ScoreMap map;
    map["Cherno"] = 5;
    map["C++"] = 2;

    for (ScoreMap::const_iterator it = map.begin(); // Const iterator
        it != map.end(); it++)
    {
        auto& key = it->first;
        auto& value = it->second;

        std::cout << key << " = " << value << std::endl;
    }

    std::cout << std::endl;

    // Improved version of code immediately above
    for (auto kv : map) // Ranged-based for loops that use iterators
    {
        auto& key = kv.first;
        auto& value = kv.second;

        std::cout << key << " = " << value << std::endl;
    }

    std::cout << std::endl;

    // C++17 structured bindings method, even more improved
    // Can retrieve key value right inside of the statement
    for (auto [key, value] : map) // Structured bindings with maps
        std::cout << key << " = " << value << std::endl;

    std::cin.get();
}