is_sorted.md

is_sorted()

Function

Returns true if the range [first,last) is sorted into ascending order.

Declaration

is_sorted(first,last);

where, first, last: Input iterators to the initial and final positions of the first sorted sequence.The range used is [first,last), which contains all the elements between first1 and last1, including the element pointed by first but not the element pointed by last.

Return value:

true if the range [first,last) is sorted into ascending order, false otherwise. If the range [first,last) contains less than two elements, the function always returns true.

Example

// is_sorted example
#include <iostream>    
#include <algorithm>    //is_sorted,prev_permutation
#include <array>        // array
using namespace std;
int main () {
 array<int,4> arr {2,4,1,3};
 do {
    prev_permutation(arr.begin(),arr.end());
    for (int& x:arr) std::cout <<' '<< x;
    cout<<endl;
    } while (!is_sorted(arr.begin(),arr.end()));
  cout << "is_sorted returned true!";
  return 0;
}

Output:

2 3 4 1
2 3 1 4
2 1 4 3
2 1 3 4
1 4 3 2
1 4 2 3
1 3 4 2
1 3 2 4
1 2 4 3
1 2 3 4
is_sorted returned true!