Editing List of data structures (section)

== Data types ==

=== Primitive types ===
{{main|Primitive type}}
*[[Boolean data type|Boolean]], [[Truth value|true]] or [[false (logic)|false]].
*[[Character (computing)|Character]]
*[[Floating-point arithmetic|Floating-point]] representation of a finite subset of the [[rationals]].
** Including [[single-precision floating-point format|single-precision]] and [[double-precision floating-point format|double-precision]] [[IEEE 754]] floats, among [[:Category:Floating point types|others]]
*[[Fixed-point arithmetic|Fixed-point]] representation of the rationals
*[[Integer (computer science)|Integer]], a direct representation of either the [[Integer|integers]] or the [[non-negative integers]]
*[[Reference (computer science)|Reference]], sometimes erroneously referred to as a [[Pointer (computer programming)|pointer]] or handle, is a value that refers to another value, possibly including itself
*[[Symbol (programming)|Symbol]], a unique identifier
*[[Enumerated type]], a [[set (mathematics)|set]] of symbols
*[[Complex data type|Complex]], representation of [[complex numbers]]

=== Composite types or non-primitive type ===
{{main|Composite type}}
*[[Array (data type)|Array]], a sequence of elements of the same type stored contiguously in memory
*[[Record (computer science)|Record]] (also called a structure or [[struct (C programming language)|struct]]), a collection of fields
*[[Product type]] (also called a tuple), a record in which the fields are not named
*[[String (computing)|String]], a sequence of characters representing text
*[[Union type|Union]], a datum which may be one of a set of types
*[[Tagged union]] (also called a ''variant'', ''discriminated union'' or ''sum type''), a union with a tag specifying which type the data is

=== Abstract data types ===
{{main|Abstract data type}}
*[[Container (data structure)|Container]]
*[[List (abstract data type)|List]]
*[[Tuple]]
*[[Associative array|Associative array, Map]]
*[[Multimap]]
*[[Set (abstract data type)|Set]]
*[[Multiset (abstract data type)|Multiset (bag)]]
*[[Stack (abstract data type)|Stack]]
*[[Queue (abstract data type)|Queue]] (example [[Priority queue]])
*[[Double-ended queue]]
*[[Graph (data structure)|Graph]] (example [[Tree (data structure)|Tree]], [[Heap (data structure)|Heap]])

Some properties of abstract data types:
{| class="wikitable"
!Structure
!Ordered?
!Uniqueness?
|-
| [[List (abstract data type)|List]]
| yes
| no
|-
| [[Associative array]]
| no
| keys (indexes) only
|-
| [[Set (abstract data type)|Set]]
| no
| yes
|-
| [[Stack (abstract data type)|Stack]]
| yes
| no
|-
| [[Multimap]]
| no
| no
|-
| [[Multiset (abstract data type)|Multiset (bag)]]
| no
| no
|-
| [[Queue (abstract data type)|Queue]] 
| yes
| no
|}

"Ordered" means that the elements of the data type have some kind of explicit order to them, where an element can be considered "before" or "after" another element. This order is usually determined by the order in which the elements are added to the structure, but the elements can be rearranged in some contexts, such as [[Sorting algorithm|sorting]] a list. For a structure that isn't ordered, on the other hand, no assumptions can be made about the ordering of the elements (although a physical implementation of these data types will often apply some kind of arbitrary ordering). "Uniqueness" means that duplicate elements are not allowed. Depending on the implementation of the data type, attempting to add a duplicate element may either be ignored, overwrite the existing element, or raise an error. The detection for duplicates is based on some inbuilt (or alternatively, user-defined) rule for comparing elements.