C++ List Library - unique() Function

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Description

The C++ function std::list::unique() Removes all consecutive duplicate elements from the list. It uses operator== for comparison.

Declaration

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

C++98

 void unique(); 

Parameters

None

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::unique() function.

 #include <iostream> #include <list> using namespace std; int main(void) { list <int> l = {1, 1, 2, 2, 3, 4, 5, 5}; cout << "List elements before unique operation" << endl; for (auto it = l.begin(); it != l.end(); ++it) cout << *it << endl; l.unique(); cout << "List elements after unique 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 −

 List elements before unique operation 1 1 2 2 3 4 5 5 List elements after unique operation 1 2 3 4 5