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Returns a reference to the element at position n in the deque container.
A similar member function, deque::at, has the same behavior as this operator function, except that deque::at is bound-checked and signals if the requested position is out of range by throwing an out_of_range exception.
Member types reference and const_reference are the reference types to the elements of the container (see deque member types).
Output:
Element n is potentially accessed or modified. Concurrently accessing or modifying other elements is safe.
Otherwise, the behavior is undefined (which may include throwing).
Reference
C library:
- <cassert> (assert.h)
- <cctype> (ctype.h)
- <cerrno> (errno.h)
-
<cfenv> (fenv.h)C++11
- <cfloat> (float.h)
-
<cinttypes> (inttypes.h)C++11
- <ciso646> (iso646.h)
- <climits> (limits.h)
- <clocale> (locale.h)
- <cmath> (math.h)
- <csetjmp> (setjmp.h)
- <csignal> (signal.h)
- <cstdarg> (stdarg.h)
-
<cstdbool> (stdbool.h)C++11
- <cstddef> (stddef.h)
-
<cstdint> (stdint.h)C++11
- <cstdio> (stdio.h)
- <cstdlib> (stdlib.h)
- <cstring> (string.h)
-
<ctgmath> (tgmath.h)C++11
- <ctime> (time.h)
-
<cuchar> (uchar.h)C++11
- <cwchar> (wchar.h)
- <cwctype> (wctype.h)
Containers:
-
<array>C++11
- <deque>
-
<forward_list>C++11
- <list>
- <map>
- <queue>
- <set>
- <stack>
-
<unordered_map>C++11
-
<unordered_set>C++11
- <vector>
-
Input/Output:
Multi-threading:
-
<atomic>C++11
-
<condition_variable>C++11
-
<future>C++11
-
<mutex>C++11
-
<thread>C++11
-
Other:
- <algorithm>
- <bitset>
-
<chrono>C++11
-
<codecvt>C++11
- <complex>
- <exception>
- <functional>
-
<initializer_list>C++11
- <iterator>
- <limits>
- <locale>
- <memory>
- <new>
- <numeric>
-
<random>C++11
-
<ratio>C++11
-
<regex>C++11
- <stdexcept>
- <string>
-
<system_error>C++11
-
<tuple>C++11
-
<type_traits>C++11
-
<typeindex>C++11
- <typeinfo>
- <utility>
- <valarray>
deque
- deque::~deque
- deque::deque
member functions
- deque::assign
- deque::at
- deque::back
- deque::begin
-
deque::cbeginC++11
-
deque::cendC++11
- deque::clear
-
deque::crbeginC++11
-
deque::crendC++11
-
deque::emplaceC++11
-
deque::emplace_backC++11
-
deque::emplace_frontC++11
- deque::empty
- deque::end
- deque::erase
- deque::front
- deque::get_allocator
- deque::insert
- deque::max_size
- deque::operator[]
- deque::operator=
- deque::pop_back
- deque::pop_front
- deque::push_back
- deque::push_front
- deque::rbegin
- deque::rend
- deque::resize
-
deque::shrink_to_fitC++11
- deque::size
- deque::swap
non-member overloads
public member function
<deque>
std::deque::operator[]
reference operator[] (size_type n);const_reference operator[] (size_type n) const;
Access element
A similar member function, deque::at, has the same behavior as this operator function, except that deque::at is bound-checked and signals if the requested position is out of range by throwing an out_of_range exception.
Parameters
- n
- Position of an element in the container.
Notice that the first element has a position of 0 (not 1).
Member type size_type is an unsigned integral type.
Return value
The element at the specified position in the container.Member types reference and const_reference are the reference types to the elements of the container (see deque member types).
Example
|
|
Output:
mydeque contains: 9 8 7 6 5 4 3 2 1 0 |
Complexity
Constant.Iterator validity
No changes.Data races
The container is accessed (neither the const nor the non-const versions modify the container).Element n is potentially accessed or modified. Concurrently accessing or modifying other elements is safe.
Exception safety
If the container size is greater than n, the function never throws exceptions (no-throw guarantee).Otherwise, the behavior is undefined (which may include throwing).
See also
- deque::at
- Access element (public member function)
- deque::front
- Access first element (public member function)
- deque::back
- Access last element (public member function)
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Spotted an error? contact us