C++ List Library - sort() Function

Description

The C++ function std::list::sort() sorts the elements of the list. The order of equal elements is preserved. It uses comparison function to compare values.

Declaration

Following is the declaration for std::list::sort() function form std::list header.

C++98

template <class Compare>
void sort (Compare comp);

Parameters

comp − comparison function object which returns boolean. It has following prototype.

bool cmp(const Type1 &ar1, const Type2 &arg2);

Return value

None

Exceptions

This member function never throws exception.

Time complexity

Linear i.e. O(n)

Example

The following example shows the usage of std::list::sort() function.

#include <iostream>
#include <list>

using namespace std;

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

int main(void) {
   list<int> l = {1, 4, 2, 5, 3};

   cout << "Contents of list before sort operation" << endl;

   for (auto it = l.begin(); it != l.end(); ++it)
      cout << *it << endl;

   /* Descending sort */
   l.sort(comp);

   cout << "Contents of list after sort operation" << endl;

   for (auto it = l.begin(); it != l.end(); ++it)
      cout << *it << endl;

   return 0;
}

Let us compile and run the above program, this will produce the following result −

Contents of list before sort operation
1
4
2
5
3
Contents of list after sort operation
5
4
3
2
1