Understanding Range Categories in C++
What are the different categories of ranges in C++?
Ranges in C++ are categorized based on the capabilities of their underlying iterators. There are many different categories of range, each with a different set of capabilities. The three most common types are:
- Forward Range: Supports one-way traversal, such as
std::forward_list. - Bidirectional Range: Supports two-way traversal, such as
std::list. - Random-Access Range: Supports direct access to any element, such as
std::vector.
Here's an example that checks the category of different ranges:
#include <vector>
#include <list>
#include <forward_list>
#include <ranges>
#include <iostream>
template <typename T>
void Log(T Range) {
if constexpr (std::ranges::forward_range<T>) {
std::cout << " - Forward Range\n";
}
if constexpr (std::ranges::bidirectional_range<T>) {
std::cout << " - Bidirectional Range\n";
}
if constexpr (std::ranges::random_access_range<T>) {
std::cout << " - Random Access Range\n";
}
}
int main() {
std::cout << "std::forward_list<int>:\n";
Log(std::forward_list<int>{1, 2, 3});
std::cout << "\nstd::list<int>:\n";
Log(std::list<int>{1, 2, 3});
std::cout << "\nstd::vector<int>:\n";
Log(std::vector<int>{1, 2, 3});
}std::forward_list<int>:
- Forward Range
std::list<int>:
- Forward Range
- Bidirectional Range
std::vector<int>:
- Forward Range
- Bidirectional Range
- Random Access RangeIterators and Ranges
This lesson offers an in-depth look at iterators and ranges, emphasizing their roles in container traversal