std::deque<T,Allocator>::front

reference front();	(1)
const_reference front() const;	(2)

Returns a reference to the first element in the container.

If empty() is true, the behavior is undefined.

(until C++26)

If empty() is true:

(since C++26)

Reference to the first element.

Constant.

For a container c, the expression c.front() is equivalent to *c.begin().

The following code uses front to access the first element of a std::deque<char>:

#include <cassert>
#include <deque>
 
int main()
{
    std::deque<char> letters{'a', 'b', 'c', 'd'};
    assert(letters.front() == 'a');
}

back	access the last element (public member function)
rendcrend (C++11)	returns a reverse iterator to the end (public member function)
begincbegin (C++11)	returns an iterator to the beginning (public member function)