C++ concepts: Container
A Container is an object used to store other objects and taking care of the management of the memory used by the objects it contains.
Contents |
[edit] Requirements
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CContainer type -
TElement type -
a,bObjects of typeC
[edit] Types
| name | type | notes |
|---|---|---|
value_type |
T |
Destructible
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reference |
lvalue of T | |
const_reference |
const lvalue of T | |
iterator |
iterator pointing to T |
ForwardIteratorconvertible to const_iterator
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const_iterator |
const iterator pointing to T |
ForwardIterator
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difference_type |
signed integer | must be the same as iterator_traits::difference_type for iterator and const_iterator
|
size_type |
unsigned integer | large enough to represent all positive values of difference_type
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[edit] Methods and operators
| expression | return type | semantics | conditions | complexity | |
|---|---|---|---|---|---|
| C(); | C | Creates an empty container | Post: u.empty() == true | Constant | |
| C(a) | C | Create a copy of a
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Pre: T must be CopyInsertablePost: a == X(a) |
Linear | |
| a = b | C& | All elements of a are destroyed or move assigned to elements of b |
Post: a == b | Linear | |
| (&a)->~C() | void | Destroy all elements and free all memory | Linear | ||
| a.begin() | (const_)iterator | Iterator to the first element | Constant | ||
| a.end() | (const_)iterator | Iterator to one passed the last element | Constant | ||
| a.cbegin()(since C++11) | const_iterator | const_cast<const C&>(a).begin() | Constant | ||
| a.cend()(since C++11) | const_iterator | const_cast<const C&>(a).end() | Constant | ||
| a == b | convertible to bool | Makes C EqualityComparable |
Pre: T must be EqualityComparable |
Linear | |
| a != b | convertible to bool | !(a==b) | Linear | ||
| a.swap(b) | void | exchanges the values of a and b | Constant[1][2] | ||
| swap(a,b) | void | a.swap(b) | Constant[1] | ||
| a.size() | size_type | distance(a.begin(),a.end()) | Constant[2] | ||
| a.max_size() | size_type | b.size() where b is the largest possible container | Constant[2] | ||
| a.empty() | convertible to bool | a.begin() == a.end() | Constant | ||
| notes | |||||
[edit] Container data races
Implementations are not required to provide any reentrancy guarantee for sequence modifications - it is not safe to push_back and read begin concurrently. However, it is required to avoid data races when the contents of the contained object in different elements of the same sequence are modified concurrently (except for vector<bool>). In other words, for a vector<int> with size greater than 1, x[1] = 5 and *x.begin() = 10 will not result in a data race.
These functions must also be considered const: begin, end, rbegin, rend, front, back, data, find, lower_bound, upper_bound, equal_range, at, and, except in AssociativeContainer and UnorderedAssociativeContainer, operator[]. Calling any of these functions concurrently will not result in a data race.
[edit] Other concepts
- C
- T