C++ Deque Library - begin() Function

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Description

The C++ function std::deque::begin() returns a random access iterator which points to the first element of the deque.

Declaration

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

C++98

iterator begin();
const_iterator begin() const;

C++11

iterator begin() noexcept;
const_iterator begin() const noexcept;

Parameters

None

Return value

If deque object is constant qualified then method returns constant random access iterator otherwise non constant random access iterator.

Exceptions

This member function never throws exception.

Time complexity

Constant i.e. O(1)

Example

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

#include <iostream>
#include <deque>

using namespace std;

int main(void) {

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

   cout << "Contents of deque are" << endl;

   for (auto it = d.begin(); it != d.end(); ++it)
      cout << *it << endl;

   return 0;
}

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

Contents of deque are
1
2
3
4
5