C++ Forward_list Library - empty() Function

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Description

The C++ function std::forward_list::empty() tests whether forward_list is empty of not. Forward_list of zero size is considered as empty.

Declaration

Following is the declaration for std::forward_list::empty() function form std::forward_list header.

C++11

bool empty() const noexcept;

Parameters

None

Return value

Returns true if forward_list is empty otherwise false.

Exceptions

This member function never throws exception.

Time complexity

Constant i.e. O(1)

Example

The following example shows the usage of std::forward_list::empty() function.

#include <iostream>
#include <forward_list>

using namespace std;

int main(void) {
   forward_list<int> fl;

   if (fl.empty())
      cout << "List is empty." << endl;

   fl.emplace_front(1);

   if (!fl.empty())
      cout << "List is not empty." << endl;

   return 0;
}

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

List is empty.
List is not empty.