std::next - cppreference.com (original) (raw)

| Defined in header | | | | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | --------------------------- | | template< class InputIt >InputIt next( InputIt it, typename std::iterator_traits<InputIt>::difference_type n = 1 ); | | (since C++11) (until C++17) | | template< class InputIt > constexpr InputIt next( InputIt it, typename std::iterator_traits<InputIt>::difference_type n = 1 ); | | (since C++17) |

Return the nth successor (or -nth predecessor if n is negative) of iterator it.

Contents

• 1 Parameters
• 2 Return value
• 3 Complexity
• 4 Possible implementation
• 5 Notes
• 6 Example
• 7 Defect reports
• 8 See also

[edit] Parameters

[edit] Return value

An iterator of type InputIt that holds the nth successor (or -nth predecessor if n is negative) of iterator it.

[edit] Complexity

Linear.

However, if InputIt additionally meets the requirements of LegacyRandomAccessIterator, complexity is constant.

[edit] Possible implementation

template constexpr // since C++17 InputIt next(InputIt it, typename std::iterator_traits::difference_type n = 1) { std::advance(it, n); return it; }

[edit] Notes

Although the expression ++c.begin() often compiles, it is not guaranteed to do so: c.begin() is an rvalue expression, and there is no LegacyInputIterator requirement that specifies that increment of an rvalue is guaranteed to work. In particular, when iterators are implemented as pointers or its operator++ is lvalue-ref-qualified, ++c.begin() does not compile, while std::next(c.begin()) does.

[edit] Example

#include #include #include   int main() { std::vector v{4, 5, 6};   auto it = v.begin(); auto nx = std::next(it, 2); std::cout << *it << ' ' << *nx << '\n';   it = v.end(); nx = std::next(it, -2); std::cout << ' ' << *nx << '\n'; }

Output:

[edit] Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

[edit] See also

| | decrement an iterator (function template) [edit] | | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | | | advances an iterator by given distance (function template) [edit] | | | returns the distance between two iterators (function template) [edit] | | | increment an iterator by a given distance or to a bound(algorithm function object)[edit] |