//

// 2.11.for.loop.cpp

// chapter 2 language usability

// modern cpp tutorial

//

// created by changkun at changkun.de

// https://github.com/changkun/modern-cpp-tutorial

//

#include <iostream>

#include <vector>

#include <algorithm>

#include <cstddef>

// A minimal custom container: any type that provides usable begin()/end()

// (whose iterators support !=, * and pre-++) can be used with range-based for,

// because the loop is just syntactic sugar over those operations.

struct IntRange {

int* data;

std::size_t n;

int* begin() const { return data; }

int* end() const { return data + n; }

};

int main() {

std::vector<int> vec = {1, 2, 3, 4};

if (auto itr = std::find(vec.begin(), vec.end(), 3); itr != vec.end()) *itr = 4;

for (auto element : vec)

std::cout << element << std::endl; // read only

for (auto &element : vec) {

element += 1; // writeable

}

for (auto element : vec)

std::cout << element << std::endl; // read only

// range-based for over a user-defined container

int arr[] = {10, 20, 30};

IntRange range{arr, 3};

for (auto&& x : range)

std::cout << x << ' ';

std::cout << std::endl;

}