Defined in header <algorithm> | ||
---|---|---|
template< class ForwardIt > bool is_sorted( ForwardIt first, ForwardIt last ); | (1) | (since C++11) |
template< class ForwardIt, class Compare > bool is_sorted( ForwardIt first, ForwardIt last, Compare comp ); | (2) | (since C++11) |
Checks if the elements in range [first, last)
are sorted in ascending order. The first version of the function uses operator<
to compare the elements, the second uses the given comparison function comp
.
Parameters
first, last | - | the range of elements to examine |
comp | - | comparison function object (i.e. an object that satisfies the requirements of Compare ) which returns true if the first argument is less than (i.e. is ordered before) the second. The signature of the comparison function should be equivalent to the following:
The signature does not need to have |
Type requirements | ||
- ForwardIt must meet the requirements of ForwardIterator . |
Return value
true
if the elements in the range are sorted in ascending order.
Complexity
linear in the distance between first
and last
.
Possible implementation
First version |
---|
template<class ForwardIt> bool is_sorted(ForwardIt first, ForwardIt last) { return std::is_sorted_until(first, last) == last; } |
Second version |
template<class ForwardIt, class Compare> bool is_sorted(ForwardIt first, ForwardIt last, Compare comp) { return std::is_sorted_until(first, last, comp) == last; } |
Example
#include <iostream> #include <algorithm> int main() { const int N = 5; int digits[N] = {3, 1, 4, 1, 5}; for (auto i : digits) std::cout << i << ' '; std::cout << ": is_sorted: " << std::is_sorted(digits, digits+N) << '\n'; std::sort(digits, digits+N); for (auto i : digits) std::cout << i << ' '; std::cout << ": is_sorted: " << std::is_sorted(digits, digits+N) << '\n'; }
Output:
3 1 4 1 5 : is_sorted: 0 1 1 3 4 5 : is_sorted: 1
See also
(C++11) | finds the largest sorted subrange (function template) |
std::experimental::parallel::is_sorted
(parallelism TS) | parallelized version of std::is_sorted (function template) |
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