#include <iostream>
#include <vector>
#include <map>

int main() {
    // 1. Basic type deduction
    auto i = 42;           // int
    auto d = 3.14;         // double
    auto s = std::string{"hello"};  // std::string

    // 2. Auto with iterators (most common use case)
    std::vector<int> nums = {1, 2, 3, 4, 5};

    // Without auto: std::vector<int>::iterator it = nums.begin();
    for (auto it = nums.begin(); it != nums.end(); ++it) {
        std::cout << *it << " ";
    }
    std::cout << "\n";

    // 3. Range-based for loop
    std::map<std::string, int> ages = {{"Alice", 30}, {"Bob", 25}};

    // Without auto: for (const std::pair<const std::string, int>& p : ages)
    for (const auto& [name, age] : ages) {
        std::cout << name << " is " << age << "\n";
    }

    // 4. Auto with functions (C++14 return type deduction)
    auto add = [](auto a, auto b) { return a + b; };
    std::cout << add(3, 4) << "\n";       // 7
    std::cout << add(1.5, 2.5) << "\n";   // 4.0

    return 0;
}