Difference between revisions of "cpp/algorithm/reverse"
From cppreference.com
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(specified in terms of iter_swap in the standard (including C++14 bugfix from LWG issue 2039)) |
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| − | Reverses the order of the elements in the range {{tt|[first, last)}} | + | Reverses the order of the elements in the range {{tt|[first, last)}} |
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| + | Behaves as if applying {{lc|std::iter_swap}} to every pair of iterators {{tt|first+i, (last-i) - 1}} for each non-negative {{tt|i < (last-first)/2}} | ||
===Parameters=== | ===Parameters=== | ||
Revision as of 19:33, 14 August 2013
| Defined in header <algorithm>
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| template< class BidirIt > void reverse( BidirIt first, BidirIt last ); |
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Reverses the order of the elements in the range [first, last)
Behaves as if applying std::iter_swap to every pair of iterators first+i, (last-i) - 1 for each non-negative i < (last-first)/2
Contents |
Parameters
| first, last | - | the range of elements to reverse |
| Type requirements | ||
Return value
(none)
Possible implementation
template<class BidirIt> void reverse(BidirIt first, BidirIt last) { while ((first != last) && (first != --last)) { std::swap(*first++, *last); } } |
Example
Run this code
#include <vector> #include <iostream> #include <algorithm> int main(int argc, char** argv) { std::vector<int> v({1,2,3}); std::reverse(std::begin(v), std::end(v)); std::cout << v[0] << v[1] << v[2] << '\n'; int a[] = {4, 5, 6, 7}; std::reverse(&a[0], &a[4]); std::cout << a[0] << a[1] << a[2] << a[3] << '\n'; }
Output:
321 7654
Complexity
linear in the distance between first and last
See also
| creates a copy of a range that is reversed (function template) |
