# <ranges>

**[<ranges>](https://en.cppreference.com/w/cpp/header/ranges)** provides the ranges library (C++20): a new way to express algorithms that works on ranges directly instead of iterator pairs. Instead of `std::sort(v.begin(), v.end())`, you write `std::ranges::sort(v)`. Range adapters like `std::views::filter` compose transformations lazily.

It's more expressive and composable than the classic iterator-based algorithms, but requires C++20 or later.

## Example

This example sorts a vector and filters even numbers using range-based algorithms and views with the pipe operator.

```cpp
// compile: g++ -std=c++20 -o rangesexample rangesexample.cpp
// run: ./rangesexample
// description: ranges library with views

#include <ranges>
#include <vector>
#include <iostream>

int main() {
    std::vector<int> nums = {1, 2, 3, 4, 5};
    
    std::ranges::sort(nums);
    
    auto evens = nums | std::views::filter([](int x) { return x % 2 == 0; });
    for (int x : evens) {
        std::cout << x << " ";
    }
    std::cout << "\n";
    
    return 0;
}
```