std::deque<T,Allocator>::begin,std::deque<T,Allocator>::cbegin (3) - Linux Man Pages

std::deque<T,Allocator>::begin,std::deque<T,Allocator>::cbegin: std::deque<T,Allocator>::begin,std::deque<T,Allocator>::cbegin

NAME

std::deque<T,Allocator>::begin,std::deque<T,Allocator>::cbegin - std::deque<T,Allocator>::begin,std::deque<T,Allocator>::cbegin

Synopsis


iterator begin(); (until C++11)
iterator begin() noexcept; (since C++11)
const_iterator begin() const; (until C++11)
const_iterator begin() const noexcept; (since C++11)
const_iterator cbegin() const noexcept; (since C++11)


Returns an iterator to the first element of the container.
If the container is empty, the returned iterator will be equal to end().
 range-begin-end.svg

Parameters


(none)

Return value


Iterator to the first element

Complexity


Constant

Example


// Run this code


  #include <iostream>
  #include <deque>
  #include <string>


  int main()
  {
   std::deque<int> ints {1, 2, 4, 8, 16};

   std::deque<std::string> fruits {"orange", "apple", "raspberry"};

   std::deque<char> empty;


   // Sums all integers in the deque ints (if any), printing only the result.

   int sum = 0;

   for (auto it = ints.cbegin(); it != ints.cend(); it++)

   sum += *it;

   std::cout << "Sum of ints: " << sum << "\n";


   // Prints the first fruit in the deque fruits, without checking if there is one.

   std::cout << "First fruit: " << *fruits.begin() << "\n";


   if (empty.begin() == empty.end())

   std::cout << "deque 'empty' is indeed empty.\n";

  }

Output:


  Sum of ints: 31
  First fruit: orange
  deque 'empty' is indeed empty.

See also


end_ returns an iterator to the end
cend (public member function)