CODEWITHSUNDEEP
c++iterator
user2138149
user2138149

Reputation: 17266

Is there an equivalent of the `at` function for iterators?

Is there an equivalent of the at function for iterators?

For example

std::vector example(10, 0);
const auto it = example.cbegin();
const auto it2 = it + 10;
std::cout << *it2 << std::endl; // does not throw

whereas with at

example.at(10); // throws

Upvotes: -1

Views: 109

Answers (1)

Eugene
Eugene

Reputation: 7688

Iterators do not have at() member function because it would violate "you only pay for what you use" C++ design principle. In a fully optimized build, a vector iterator is equivalent to a pointer. To support at(), the iterator must carry valid range information - even when at() is not used. There are implementation-specific debug builds with "checked iterators" that carry this extra info and fail an assert in case of invalid iterator use.

Upvotes: 1

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