< cpp‎ | container
Revision as of 15:21, 28 December 2012 by Nate (Talk | contribs)

Defined in header <vector>

    class T,
    class Allocator = std::allocator<T>

> class vector;

std::vector is a sequence container that encapsulates dynamic size arrays.

The elements are stored contiguously, which means that elements can be accessed not only through iterators, but also using offsets on regular pointers to elements. This means that a pointer to an element of a vector may be passed to any function that expects a pointer to an element of an array.

The storage of the vector is handled automatically, being expanded and contracted as needed. Vectors usually occupy more space than static arrays, because more memory is allocated to handle future growth. This way a vector does not need to reallocate each time an element is inserted, but only when the additional memory is exhausted. The total amount of allocated memory can be queried using Template:rlf function. Extra memory can be returned to the system via a call to Template:rlf.

Reallocations are usually costly operations in terms of performance. Template:rlf function can be used to eliminate reallocations if the number of elements is known beforehand.

The complexity (efficiency) of common operations on vectors is as follows:

  • Random access - constant O(1)
  • Insertion or removal of elements at the end - amortized constant O(1)
  • Insertion or removal of elements - linear in distance to the end of the vector O(n)

std::vector meets the requirements of Container, AllocatorAwareContainer, SequenceContainer and ReversibleContainer.



The standard library provides a specialization of std::vector for the type bool, which is optimized for space efficiency.

Template:cpp/container/dcl list vector bool

Member types

Template:cpp/container/dcl list value typeTemplate:cpp/container/dcl list allocator typeTemplate:cpp/container/dcl list size typeTemplate:cpp/container/dcl list difference typeTemplate:cpp/container/dcl list referenceTemplate:cpp/container/dcl list const referenceTemplate:cpp/container/dcl list pointerTemplate:cpp/container/dcl list const pointerTemplate:cpp/container/dcl list iteratorTemplate:cpp/container/dcl list const iteratorTemplate:cpp/container/dcl list reverse iteratorTemplate:cpp/container/dcl list const reverse iterator
Member type Definition

Member functions

Template:cpp/container/dcl list constructorTemplate:cpp/container/dcl list destructorTemplate:cpp/container/dcl list operator=Template:cpp/container/dcl list assignTemplate:cpp/container/dcl list get allocatorTemplate:cpp/container/dcl list atTemplate:cpp/container/dcl list operator atTemplate:cpp/container/dcl list frontTemplate:cpp/container/dcl list backTemplate:cpp/container/dcl list dataTemplate:cpp/container/dcl list beginTemplate:cpp/container/dcl list endTemplate:cpp/container/dcl list rbeginTemplate:cpp/container/dcl list rendTemplate:cpp/container/dcl list emptyTemplate:cpp/container/dcl list sizeTemplate:cpp/container/dcl list max sizeTemplate:cpp/container/dcl list reserveTemplate:cpp/container/dcl list capacityTemplate:cpp/container/dcl list shrink to fitTemplate:cpp/container/dcl list clearTemplate:cpp/container/dcl list insertTemplate:cpp/container/dcl list emplaceTemplate:cpp/container/dcl list eraseTemplate:cpp/container/dcl list push backTemplate:cpp/container/dcl list emplace backTemplate:cpp/container/dcl list pop backTemplate:cpp/container/dcl list resizeTemplate:cpp/container/dcl list swap
Element access

Non-member functions

Template:cpp/container/dcl list operator cmpTemplate:cpp/container/dcl list swap2