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Random Access Container

Category: containers Component type: concept


A Random Access Container is a Reversible Container whose iterator type is a Random Access Iterator. It provides amortized constant time access to arbitrary elements.

Refinement of

Reversible Container

Associated types

No additional types beyond those defined in Reversible Container. However, the requirements for the iterator type are strengthened: it must be a Random Access Iterator.


X A type that is a model of Random Access Container
a, b Object of type X
T The value type of X


Valid expressions

In addition to the expressions defined in Reversible Container, the following expressions must be valid.
Name Expression Type requirements Return type
Element access a[n] n is convertible to size_type reference if a is mutable, const_reference otherwise

Expression semantics

Semantics of an expression is defined only where it is not defined in Reversible Container, or where there is additional information.
Name Expression Precondition Semantics Postcondition
Element access a[n] 0 <= n < a.size() Returns the nth element from the beginning of the container.  

Complexity guarantees

The run-time complexity of element access is amortized constant time.


Element access The element returned by a[n] is the same as the one obtained by incrementing a.begin() n times and then dereferencing the resulting iterator.



See also

The Iterator overview, Random Access Iterator, Sequence

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