Editing Dynamic array (section)

== Growth factor ==
The growth factor for the dynamic array depends on several factors including a space-time trade-off and algorithms used in the memory allocator itself. For growth factor ''a'', the average time per insertion operation is {{citation needed span|text=about ''a''/(''a''−1), while the number of wasted cells is bounded above by (''a''−1)''n''|date=January 2018}}. If memory allocator uses a [[First fit algorithm|first-fit allocation]] algorithm, then growth factor values such as ''a''=2 can cause dynamic array expansion to run out of memory even though a significant amount of memory may still be available.<ref name=":0">{{Cite web|title = C++ STL vector: definition, growth factor, member functions|url = http://www.gahcep.com/cpp-internals-stl-vector-part-1/|access-date = 2015-08-05|archive-url = https://web.archive.org/web/20150806162750/http://www.gahcep.com/cpp-internals-stl-vector-part-1/|archive-date = 2015-08-06|url-status = dead}}</ref> There have been various discussions on ideal growth factor values, including proposals for the [[golden ratio]] as well as the value 1.5.<ref>{{Cite web|url = https://groups.google.com/forum/#!topic/comp.lang.c++.moderated/asH_VojWKJw%5B1-25%5D|title = vector growth factor of 1.5|website = comp.lang.c++.moderated|publisher = Google Groups|access-date = 2015-08-05|archive-date = 2011-01-22|archive-url = http://arquivo.pt/wayback/20110122130054/https://groups.google.com/forum/#!topic/comp.lang.c++.moderated/asH_VojWKJw%5B1-25%5D|url-status = dead}}</ref> Many textbooks, however, use ''a''&nbsp;=&nbsp;2 for simplicity and analysis purposes.<ref name="gt-ad">{{citation|first1=Michael T.|last1=Goodrich|author1-link=Michael T. Goodrich|first2=Roberto|last2=Tamassia|author2-link=Roberto Tamassia|title=Algorithm Design: Foundations, Analysis and Internet Examples|publisher=Wiley|year=2002|contribution=1.5.2 Analyzing an Extendable Array Implementation|pages=39–41}}.</ref><ref name="clrs">{{Introduction to Algorithms|chapter=17.4 Dynamic tables|edition=2|pages=416–424}}</ref>

Below are growth factors used by several popular implementations:
{| class="wikitable"
!Implementation
!Growth factor (''a'')
|-
|Java ArrayList<ref name="java_util_ArrayList" />
|1.5 (3/2)
|-
|[[Python (programming language)|Python]] PyListObject<ref>[https://github.com/python/cpython/blob/bace59d8b8e38f5c779ff6296ebdc0527f6db14a/Objects/listobject.c#L58 List object implementation] from github.com/python/cpython/, retrieved 2020-03-23.</ref>
|~1.125 (n + (n >> 3))
|-
|[[Microsoft Visual C++]] 2013<ref>{{Cite web|title = Dissecting the C++ STL Vector: Part 3 - Capacity & Size|url = https://hadibrais.wordpress.com/2013/11/15/dissecting-the-c-stl-vector-part-3-capacity/|website = Micromysteries|access-date = 2015-08-05|first = Hadi|last = Brais| date=15 November 2013 }}</ref>
|1.5 (3/2)
|-
|[[G++]] 5.2.0<ref name=":0" />
|2
|-
|[[Clang]] 3.6<ref name=":0" />
|2
|-
|Facebook folly/FBVector<ref>{{Cite web|title = facebook/folly|url = https://github.com/facebook/folly/blob/master/folly/docs/FBVector.md|website = GitHub|access-date = 2015-08-05}}</ref>
|1.5 (3/2)
|-
|[[Unreal Engine]] TArray<ref>{{Cite web |date=2025-02-26 |title=Nested TArrays in structs and memory |url=https://forums.unrealengine.com/t/nested-tarrays-in-structs-and-memory/2357416/3 |access-date=2025-05-26 |website=Epic Developer Community Forums |language=en}}</ref>
|~1.375 (n + ((3 * n) >> 3))
|-
|Rust Vec<ref>{{Cite web|title=rust-lang/rust|url=https://github.com/rust-lang/rust/blob/fd4b177aabb9749dfb562c48e47379cea81dc277/src/liballoc/raw_vec.rs#L443|access-date=2020-06-09|website=GitHub|language=en}}</ref>
|2
|-
|[[Go (programming language)|Go]] slices<ref>{{Cite web|title = golang/go|url = https://github.com/golang/go/blob/master/src/runtime/slice.go#L188|website=GitHub|access-date = 2021-09-14}}</ref>
|between 1.25 and 2
|-
|[[Nim (programming language)|Nim]] sequences<ref>{{Cite web |title=The Nim memory model |url=http://zevv.nl/nim-memory/#_growing_a_seq |access-date=2022-05-24 |website=zevv.nl}}</ref>
|2
|-
|[[Steel Bank Common Lisp|SBCL]] ([[Common Lisp]]) vectors<ref>{{Cite web |title = sbcl/sbcl|url= https://github.com/sbcl/sbcl/blob/master/src/code/array.lisp#L1200-L1204|website=GitHub|access-date=2023-02-15}}</ref>
|2
|-
|[[C Sharp (programming language)|C#]] ([[.NET]] 8) List
|2
|}