Sort function is used to sort a given range in ascending order. This function is defined in the header algorithm. There are two version are defined of it.

template< class RandomIt >
void sort( RandomIt first, RandomIt last );

template< class RandomIt, class Compare >
void sort( RandomIt first, RandomIt last, Compare comp );

The first version sorts the range in ascending order. Second version uses comparison function comp in which sort function works according to comp function.

About the parameters

first
It is the initial position of the range which is included in the range.

last
It is the position of the range which is excluded in the range.

comp
It is the comparison function, it returns a value convertible to bool.

Sample program using the first version

#include <iostream>
#include <vector>
#include <algorithm>


using namespace std;

int main()
{
        vector <int> v;
        vector<int> :: iterator it;

        for (int i = 10; i >= 0; i--) {
                v.push_back(i);
        }

        //Before sort printing the elements of vector
        for (it = v.begin(); it != v.end(); it++) {
                cout << *it << " ";
        }
        cout << endl;

        sort(v.begin(),v.end()); //applying first version of sort (the default sort)

        //After sort printing the elements of vector
        for (it = v.begin(); it != v.end(); it++) {
                cout << *it << " ";
        }
        cout << endl;

        return 0;
}

Output of the above program

Before applying Sort Function
Output : 10 9 8 7 6 5 4 3 2 1 0 
After applying Sort Function
Output : 0 1 2 3 4 5 6 7 8 9 10

Sample program using the second version

#include <iostream>
#include <vector>
#include <algorithm>


using namespace std;

int main()
{
        vector <int> v;
        vector<int> :: iterator it;

        for (int i = 0; i <= 10; i++) {
                v.push_back(i);
        }

        cout << "Before applying Sort Function\n";
        cout << "Output : ";
        for (it = v.begin(); it != v.end(); it++) {
                cout << *it << " ";
        }
        cout << endl;

        struct {
                bool operator()(int a, int b)
                {
                        return a > b;
                }
        } comp;

        // sort function using the second version
        sort(v.begin(),v.end(),comp);

        cout << "After applying Sort Function\n";
        cout << "Output : ";
        for (it = v.begin(); it != v.end(); it++) {
                cout << *it << " ";
        }
        cout << endl;

        return 0;
}

Output of the above program

Before applying Sort Function
Output : 0 1 2 3 4 5 6 7 8 9 10 
After applying Sort Function
Output : 10 9 8 7 6 5 4 3 2 1 0 

Time Complexity of sort function is

O(N log N)