C++ Deque Library - back() Function


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Description

The C++ function std::deque::back() returns a reference to the last element of the deque. Calling this function on empty causes undefined behavior.

Declaration

Following is the declaration for std::deque::back() function form std::deque header.

C++98

reference back();
const_reference back() const;

Parameters

None

Return value

Returns a reference to the last element. If deque object is contant qualified then method returns constant reference otherwise non constant reference.

Exceptions

Calling this method on empty causes undefined behavior.

Time complexity

Constant i.e. O(1)

Example

The following example shows the usage of std::deque::back() function.

#include <iostream>
#include <deque>

using namespace std;

int main(void) {

   deque<int> d = {1, 2, 3, 4, 5};

   cout << "Last element of deque = " << d.back() << endl;

   return 0;
}

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

Last element of deque = 5
deque.htm
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