sort

Arranges the elements in a specified range into a nondescending order or according to an ordering criterion specified by a binary predicate.

template<class RandomAccessIterator>
   void sort(
      RandomAccessIterator first, 
      RandomAccessIterator last
   );
template<class RandomAccessIterator, class Predicate>
   void sort(
      RandomAccessIterator first, 
      RandomAccessIterator last, 
      Predicate comp
   );

Parameters

• first
  A random-access iterator addressing the position of the first element in the range to be sorted.

• last
  A random-access iterator addressing the position one past the final element in the range to be sorted.

• comp
  User-defined predicate function object that defines the comparison criterion to be satisfied by successive elements in the ordering. This binary predicate takes two arguments and returns true if the two arguments are in order and false otherwise. This comparator function must impose a strict weak ordering on pairs of elements from the sequence. For more information, see Algorithms.

Remarks

The range referenced must be valid; all pointers must be dereferenceable and within the sequence the last position is reachable from the first by incrementation.

Elements are equivalent, but not necessarily equal, if neither is less than the other. The sort algorithm is not stable and so does not guarantee that the relative ordering of equivalent elements will be preserved. The algorithm stable_sort does preserve this original ordering.

The average of a sort complexity is O(N log N), where N = last – first.

Example

// alg_sort.cpp
// compile with: /EHsc
#include <vector>
#include <algorithm>
#include <functional>      // For greater<int>( )
#include <iostream>

// Return whether first element is greater than the second
bool UDgreater ( int elem1, int elem2 )
{
   return elem1 > elem2;
}

int main( )
{
   using namespace std;
   vector <int> v1;
   vector <int>::iterator Iter1;

   int i;
   for ( i = 0 ; i <= 5 ; i++ )
   {
      v1.push_back( 2 * i );
   }

   int ii;
   for ( ii = 0 ; ii <= 5 ; ii++ )
   {
      v1.push_back( 2 * ii + 1 );
   }

   cout << "Original vector v1 = ( " ;
   for ( Iter1 = v1.begin( ) ; Iter1 != v1.end( ) ; Iter1++ )
      cout << *Iter1 << " ";
   cout << ")" << endl;

   sort( v1.begin( ), v1.end( ) );
   cout << "Sorted vector v1 = ( " ;
   for ( Iter1 = v1.begin( ) ; Iter1 != v1.end( ) ; Iter1++ )
      cout << *Iter1 << " ";
   cout << ")" << endl;

   // To sort in descending order. specify binary predicate
   sort( v1.begin( ), v1.end( ), greater<int>( ) );
   cout << "Resorted (greater) vector v1 = ( " ;
   for ( Iter1 = v1.begin( ) ; Iter1 != v1.end( ) ; Iter1++ )
      cout << *Iter1 << " ";
   cout << ")" << endl;

   // A user-defined (UD) binary predicate can also be used
   sort( v1.begin( ), v1.end( ), UDgreater );
   cout << "Resorted (UDgreater) vector v1 = ( " ;
   for ( Iter1 = v1.begin( ) ; Iter1 != v1.end( ) ; Iter1++ )
      cout << *Iter1 << " ";
   cout << ")" << endl;
}

Original vector v1 = ( 0 2 4 6 8 10 1 3 5 7 9 11 )
Sorted vector v1 = ( 0 1 2 3 4 5 6 7 8 9 10 11 )
Resorted (greater) vector v1 = ( 11 10 9 8 7 6 5 4 3 2 1 0 )
Resorted (UDgreater) vector v1 = ( 11 10 9 8 7 6 5 4 3 2 1 0 )

Requirements

Header: <algorithm>

Namespace: std

See Also

Reference

Standard Template Library