std::is_sorted

From cppreference.com
 
 
 
Defined in header <algorithm>
template< class ForwardIterator >
bool is_sorted( ForwardIterator first, ForwardIterator last );
(1) (since C++11)
template< class ForwardIterator, class Compare >
bool is_sorted( ForwardIterator first, ForwardIterator 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.

Contents

[edit] Parameters

first, last - the range of elements to examine
comp - comparison function which returns ​true if the first argument is less than the second.

The signature of the comparison function should be equivalent to the following:

bool cmp(const Type1 &a, const Type2 &b);

The signature does not need to have const &, but the function must not modify the objects passed to it.
The types  Type1 and  Type2 must be such that an object of type ForwardIterator can be dereferenced and then implicitly converted to both of them. ​

[edit] Return value

true if the elements in the range are sorted in ascending order

[edit] Complexity

linear in the distance between first and last

[edit] Possible implementation

[edit] 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

[edit] See also

finds the largest sorted subrange
(function template)