{{Short description|Multidimensional data structure}} [[File:Jagged Array Representation.png|thumb|right|alt=numArr = [[1, 2, 3], [4, 5, 6, 7], [8, 9]]|Memory layout of a jagged array]] In computer science, a '''jagged array''', also known as a '''ragged array'''<ref>{{cite book |last=King |first=K. N. |author-link= |date= 2008|title=C Programming |url= |location= |publisher=W. W. Norton |page=301 |isbn=978-0-393-97950-3}}</ref> or '''irregular array'''<ref>{{Cite book |title=Handbook of Data Structures and Applications |publisher=CRC Press |year=2004}}</ref> is an array of arrays of which the member arrays can be of different lengths,<ref name="LibertyMacDonald2008">{{cite book|author1=Jesse Liberty|author2=Brian MacDonald|title=Learning C# 3.0|url=https://books.google.com/books?id=CgLgh5vQcPgC&pg=PA210|date=18 November 2008|publisher=O'Reilly Media, Inc.|isbn=978-0-596-55420-0|pages=210–}}</ref> producing rows of jagged edges when visualized as output. In contrast, two-dimensional arrays are always rectangular<ref name="Box2002">{{cite book|author=Don Box|title=Essential .Net: The Common Language Runtime|url=https://books.google.com/books?id=Kl1DVZ8wTqcC&pg=PA138|year=2002|publisher=Addison-Wesley Professional|isbn=978-0-201-73411-9|pages=138}}</ref> so jagged arrays should not be confused with multidimensional arrays, but the former is often used to emulate the latter.
Jagged array can be implemented with Iliffe vector data structure in languages such as Java, PHP, Python (multidimensional lists), Ruby, C#.NET, Visual Basic.NET, Perl, JavaScript, Objective-C, Swift, and Atlas Autocode.
==Examples== In C# and Java<ref>{{Cite news|url=https://www.geeksforgeeks.org/jagged-array-in-java/|title=Jagged Array in Java - GeeksforGeeks|date=2016-02-03|work=GeeksforGeeks|access-date=2018-08-13|language=en-US}}</ref> jagged arrays can be created with the following code:<ref name="DeitelDeitel2008">{{cite book|author1=Paul J. Deitel|author2=Harvey M. Deitel|title=C# 2008 for Programmers|url=https://books.google.com/books?id=sYzx_mZy0twC&pg=PA40|date=26 September 2008|publisher=Pearson Education|isbn=978-0-13-701188-9|pages=40}}</ref> <syntaxhighlight lang="csharp"> int[][] c; c = new int[2][]; // creates 2 rows c[0] = new int[5]; // 5 columns for row 0 c[1] = new int[3]; // create 3 columns for row 1 </syntaxhighlight>
In C and C++, a jagged array can be created (on the stack) using the following code:
<syntaxhighlight lang="c"> int jagged_row0[] = {0,1}; int jagged_row1[] = {1,2,3}; int *jagged[] = { jagged_row0, jagged_row1 }; </syntaxhighlight>
In C/C++, jagged arrays can also be created (on the heap) with an array of pointers:
<syntaxhighlight lang="c"> int *jagged[5];
jagged[0] = malloc(sizeof(int) * 10); jagged[1] = malloc(sizeof(int) * 3); </syntaxhighlight>
In C++/CLI, jagged array can be created with the code:<ref>{{cite web|title=Jagged Arrays|url=http://www.functionx.com/cppcli/arrays/jagged.htm|website=FunctionX|accessdate=26 November 2014}}</ref> <syntaxhighlight lang="cpp"> using namespace System; int main() { array<array<double> ^> ^ Arrayname = gcnew array <array<double> ^> (4); // array contains 4 //elements return 0; } </syntaxhighlight>
In Fortran, a jagged array can be created using derived types with allocatable component(s):
<syntaxhighlight lang="fortran"> type :: Jagged_type integer, allocatable :: row(:) end type Jagged_type type(Jagged_type) :: Jagged(3) Jagged(1)%row = [1] Jagged(2)%row = [1,2] Jagged(3)%row = [1,2,3] </syntaxhighlight>
In Python, jagged arrays are not native but one can use list comprehensions to create a multi-dimensional list which supports any dimensional matrix:<ref>{{cite web|title=Lists in Python Demystified|url=http://alvin.io/lists-in-python-demystified-part-2/|website=Alvin.io|accessdate=31 January 2016|archive-date=15 October 2016|archive-url=https://web.archive.org/web/20161015050710/http://alvin.io/lists-in-python-demystified-part-2/|url-status=dead}}</ref>
<syntaxhighlight lang="python"> multi_list_3d = [[[] for i in range(3)] for i in range(3)] # Produces: [[[], [], []], [[], [], []], [[], [], []]]
multi_list_5d = [[[] for i in range(5)] for i in range(5)] # Produces: [[[], [], [], [], []], [[], [], [], [], []], [[], [], [], [], []], [[], [], [], [], []], [[], [], [], [], []]] </syntaxhighlight>
==See also== * Variable-length array * Iliffe vector
==References== {{reflist}}
Category:Arrays Category:Articles with example Python (programming language) code