C++ Deque Library - pop_front() Function

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Description

The C++ function std::deque::pop_front() removes frist element from deque and reduces size of deque by one.

Declaration

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

C++98

void pop_front();

Parameters

None

Return value

None.

Exceptions

This member function never throws exception. Calling this function on empty deque causes undefined behavior.

Time complexity

Constant i.e. O(1)

Example

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

#include <iostream>
#include <deque>

using namespace std;

int main(void) {

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

   cout << "Contents of deque before pop_front operation." << endl;

   for (int i = 0; i < d.size(); ++i)
      cout << d[i] << endl;

   d.pop_front();
   d.pop_front();

   cout << endl;

   cout << "Contents of deque before pop_front operation." << endl;

   for (int i = 0; i < d.size(); ++i)
      cout << d[i] << endl;

   return 0;
}

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

Contents of deque before pop_front operation.
1
2
3
4
5

Contents of deque before pop_front operation.
3
4
5