C++ List Library - operator< Function

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Description

The C++ function std::list::operator< tests whether first list is less than other or not.

Declaration

Following is the declaration for std::list::operator< function form std::list header.

C++98

template <class T, class Alloc>
bool operator<  (const list<T,Alloc>& first, const list<T,Alloc>& second);

Parameters

• first − First list object.

• second − Second list object of same type.

Return value

Returns true if first list is less than second otherwise false.

Exceptions

This function never throws exception.

Time complexity

Linear i.e. O(n)

Example

The following example shows the usage of std::list::operator< function.

#include <iostream>
#include <list>

using namespace std;

int main(void) {
   list<int> l1 = {1, 2, 3};
   list<int> l2 = {1, 2, 3, 4};

   if (l1 < l2)
      cout << "List l1 is less that l2" << endl;

   l2.pop_back();

   if (!(l1 < l2))
      cout << "List l1 is not less that l2" << endl;

   return 0;
}

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

List l1 is less that l2
List l1 is not less that l2