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std::array<T,N>::front

From cppreference.com
< cpp‎ | container‎ | array
 
 
 
 
reference front();
(1) (since C++11)
(constexpr since C++17)
const_reference front() const;
(2) (since C++11)
(constexpr since C++14)

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:

  • If the implementation is hardened, a contract violation occurs. Moreover, if the contract-violation handler returns under “observe” evaluation semantic, the behavior is undefined.
  • If the implementation is not hardened, the behavior is undefined.
(since C++26)

Contents

[edit] Return value

Reference to the first element.

[edit] Complexity

Constant.

[edit] Notes

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

[edit] Example

The following code uses front to display the first element of a std::array<char, 4>:

#include <cassert>
#include <array>
 
int main()
{
    std::array<char, 4> letters{'a', 'b', 'c', 'd'};
    assert(letters.front() == 'a');
}

[edit] See also

access the last element
(public member function) [edit]
returns a reverse iterator to the end
(public member function) [edit]
returns an iterator to the beginning
(public member function) [edit]
direct access to the underlying contiguous storage
(public member function) [edit]