Allocators are classes that define memory models to be used by some parts of the Standard Library, and most specifically, by
STL containers.
This section describes the
default allocator template allocator (lowercase). This is the allocator that all standard containers will use if their last (and optional) template parameter is not specified, and is the only predefined allocator in the standard library.
Other allocators may be defined. Any class having the same members as this
default allocator and following its minimum requirements can be used as an allocator -- notice that only under very specific circumstances this is needed.
Technically, a memory model described by allocators might be specialized for each type of object to be allocated and even may store local data for each container they work with. Although this does not happen with the default
allocator.
The class template of
allocator is declared as:
| |
template < class T > class allocator;
|
Taking one template parameter (which is assumed to be
T in this entire reference).
Member types
| member | definition in allocator | represents |
|---|
| value_type | T | Element type |
| pointer | T* | Pointer to element |
| reference | T& | Reference to element |
| const_pointer | const T* | Constant pointer to element |
| const reference | const T& | Constant reference to element |
| size_type | size_t | Quantities of elements |
| difference_type | ptrdiff_t | Difference between two pointers |
Member functions
| (constructor) | Construct allocator object (public member function) |
| address | Return address (public member function) |
| allocate | Allocate block of storage (public member function) |
| deallocate | Release block of storage (public member function) |
| max_size | Maximum size possible to allocate (public member function) |
| construct | Construct an object (public member function) |
| destroy | Destroy an object (public member function) |
