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× C++ Standard Library C++ STL Library


The C++ algorithm::sort function is used to sort the elements in the range [first,last) into increasing order. The elements are compared using operator< (in first version) or comp (in second version). Equivalent elements are not guaranteed to preserve their original relative order.

Syntax

//default version
template <class RandomAccessIterator>
  void sort (RandomAccessIterator first, RandomAccessIterator last);

//custom version
template <class RandomAccessIterator, class Compare>
  void sort (RandomAccessIterator first, RandomAccessIterator last, 
             Compare comp);

Parameters

first Specify initial position of the random-access iterator of the sequence to be sorted. The range used is [first,last).
last Specify final position of the random-access iterator of the sequence to be sorted. The range used is [first,last).
comp Specify a binary function that accepts two element as arguments, and returns a value convertible to bool. The returned value indicates whether the first argument is considered to go before the second using the strict weak ordering it defines.

Return Value

None.

Time Complexity

On Average, Linearithmic i.e, Θ(nlog(n)).

Example:

In the below example, the algorithm::sort function is used to sort the given vector.

#include <iostream>
#include <algorithm>
#include <vector>
using namespace std;

int main (){
  vector<int> Vec= {10, 60, 50, 30, 40, 20};

  cout<<"Vec contains: \n";
  for(int i = 0; i < Vec.size(); i++)
    cout<<Vec[i]<<" ";   

  //sorting the vector
  sort(Vec.begin(), Vec.end());

  cout<<"\n\n";
  cout<<"Sorted Vec contains: \n";
  for(int i = 0; i < Vec.size(); i++)
    cout<<Vec[i]<<" ";   

  return 0;
}

The output of the above code will be:

Vec contains: 
10 60 50 30 40 20 

Sorted Vec contains: 
10 20 30 40 50 60 

Example:

The below example shows how to use comp with algorithm::sort function to sort the vector in decreasing order.

#include <iostream>
#include <algorithm>
#include <vector>
using namespace std;

bool greater_than (int i, int j) {
  return (i>j);
}

int main (){
  vector<int> Vec= {10, 60, 50, 30, 40, 20};

  cout<<"Vec contains: \n";
  for(int i = 0; i < Vec.size(); i++)
    cout<<Vec[i]<<" ";   

  //sorting the vector
  sort(Vec.begin(), Vec.end(), greater_than);

  cout<<"\n\n";
  cout<<"Sorted Vec contains: \n";
  for(int i = 0; i < Vec.size(); i++)
    cout<<Vec[i]<<" ";   

  return 0;
}

The output of the above code will be:

Vec contains: 
10 60 50 30 40 20 

Sorted Vec contains: 
60 50 40 30 20 10 

❮ C++ - Algorithm