std::deque<T,Allocator>:: operator[]
|
reference operator
[
]
(
size_type pos
)
;
|
(1) | (constexpr since C++26) |
|
const_reference operator
[
]
(
size_type pos
)
const
;
|
(2) | (constexpr since C++26) |
Returns a reference to the element at specified location pos .
|
If pos < size ( ) is false , the behavior is undefined. |
(until C++26) |
|
If pos < size ( ) is false :
|
(since C++26) |
Contents |
Parameters
| pos | - | position of the element to return |
Return value
Reference to the requested element.
Complexity
Constant.
Notes
Unlike std::map::operator[] , this operator never inserts a new element into the container. Accessing a nonexistent element through this operator is undefined behavior , unless the implementation is hardened (since C++26) .
Example
The following code uses operator [ ] to read from and write to a std:: deque < int > :
#include <deque> #include <iostream> int main() { std::deque<int> numbers{2, 4, 6, 8}; std::cout << "Second element: " << numbers[1] << '\n'; numbers[0] = 5; std::cout << "All numbers:"; for (auto i : numbers) std::cout << ' ' << i; std::cout << '\n'; }
Output:
Second element: 4 All numbers: 5 4 6 8
See also
|
access specified element with bounds checking
(public member function) |