std::vector<bool>

From cppreference.com
< cpp‎ | container
Defined in header <vector>
template<class Allocator>
class vector<bool, Allocator>;

std::vector<bool> is a space-efficient specialization of std::vector for the type bool.

The manner in which std::vector<bool> is made space efficient (as well as whether it is optimized at all) is implementation defined. One potential optimization involves coalescing vector elements such that each element occupies a single bit instead of sizeof(bool) bytes.

std::vector<bool> behaves similarly to std::vector, but in order to be space efficient, it:

  • Does not necessarily store its elements as a contiguous array (so &v[0] + n != &v[n])
  • Exposes class std::vector<bool>::reference as a method of accessing individual bits. In particular, objects of this class are returned by operator[] by value.
  • Does not use std::allocator_traits::construct to construct bit values.

Contents

[edit] Member types

Member type Definition
value_type bool
allocator_type Allocator
size_type implementation-defined
difference_type implementation-defined
proxy class representing a reference to a single bool
(class)
const_reference bool
pointer implementation-defined
const_pointer implementation-defined
iterator implementation-defined
const_iterator implementation-defined
reverse_iterator std::reverse_iterator<iterator>
const_reverse_iterator std::reverse_iterator<const_iterator>

[edit] Member functions

constructs the vector
(public member function of std::vector)
destructs the vector
(public member function of std::vector)
assigns values to the container
(public member function of std::vector)
assigns values to the container
(public member function of std::vector)
returns the associated allocator
(public member function of std::vector)
Element access
access specified element with bounds checking
(public member function of std::vector)
access specified element
(public member function of std::vector)
access the first element
(public member function of std::vector)
access the last element
(public member function of std::vector)
Iterators
returns an iterator to the beginning
(public member function of std::vector)
returns an iterator to the end
(public member function of std::vector)
returns a reverse iterator to the beginning
(public member function of std::vector)
returns a reverse iterator to the end
(public member function of std::vector)
Capacity
checks whether the container is empty
(public member function of std::vector)
returns the number of elements
(public member function of std::vector)
returns the maximum possible number of elements
(public member function of std::vector)
reserves storage
(public member function of std::vector)
returns the number of elements that can be held in currently allocated storage
(public member function of std::vector)
Modifiers
clears the contents
(public member function of std::vector)
inserts elements
(public member function of std::vector)
(since C++14)
constructs element in-place
(public member function of std::vector)
erases elements
(public member function of std::vector)
adds an element to the end
(public member function of std::vector)
(C++14)
constructs elements in-place at the end
(public member function of std::vector)
removes the last element
(public member function of std::vector)
changes the number of elements stored
(public member function of std::vector)
swaps the contents
(public member function of std::vector)
vector<bool> specific modifiers
flips all the bits
(public member function)
[static]
swaps two std::vector<bool>::references
(public static member function)

[edit] Non-member functions

lexicographically compares the values in the vector
(function template)
specializes the std::swap algorithm
(function template)

[edit] Helper classes

hash support for std::vector<bool>
(class template specialization)

[edit] Notes

If the size of the bitset is known at compile time, std::bitset may be used, which offers a richer set of member functions. In addition, boost::dynamic_bitset exists as an alternative to std::vector<bool>.

Since its representation may by optimized, std::vector<bool> does not necessarily meet all Container or SequenceContainer requirements. For example, because std::vector<bool>::iterator is implementation-defined, it may not satisfy the ForwardIterator requirement. Use of algorithms such as std::search that require ForwardIterators may result in either compile-time or run-time errors.