Handling Out-of-Bounds Errors in std::ranges::subrange

Out-of-bounds errors can be tricky when working with std::ranges::subrange because it doesn't perform bounds checking.

This means you need to be cautious and ensure you're accessing valid elements within the range. Here are some strategies to handle out-of-bounds errors effectively:

Check the Range Size

Before accessing elements, you can check the size of the subrange to ensure the index is within bounds. This is useful when you need to access elements by index in a random access range like std::vector.

1#include <iostream>
2#include <vector>
3#include <ranges>
4
5int main() {
6  std::vector<int> Nums{1, 2, 3, 4, 5};
7  std::ranges::subrange View{Nums};
8
9  std::size_t index = 3;
10
11  if (index < View.size()) { 
12    std::cout
13      << "Element at index " << index << ": "
14      << View[index];
15  } else {
16    std::cout << "Index out of bounds"; 
17  }
18}

1Element at index 3: 4

Using Iterators

When working with iterators, ensure that the iterator is within the valid range. This can be done by comparing the iterator with begin() and end() of the subrange.

1#include <iostream>
2#include <ranges>
3#include <vector>
4
5int main() {
6  std::vector<int> Nums{1, 2, 3, 4, 5};
7  std::ranges::subrange View{Nums};
8
9  auto it = View.begin();
10  std::advance(it, 3);
11
12  if (it != View.end()) {  
13    std::cout << "Element: " << *it;
14  } else {
15    std::cout << "Iterator out of bounds";  
16  }
17}

1Element: 4

Avoiding Out-of-Bounds Access

To prevent out-of-bounds errors, always use range-based loops or algorithms that naturally avoid such issues. For example, using a range-based for loop or standard algorithms like std::ranges::for_each().

1#include <iostream>
2#include <vector>
3#include <ranges>
4#include <algorithm>
5
6void Log(int x) { std::cout << x << ", "; }
7
8int main() {
9  std::vector<int> Nums{1, 2, 3, 4, 5};
10  std::ranges::subrange View{Nums};
11
12  std::ranges::for_each(View, Log); 
13}

11, 2, 3, 4, 5,

By implementing these strategies, you can effectively handle and avoid out-of-bounds errors when working with std::ranges::subrange.