Jagged array
{{Short description|Kind of multidimensional data structure}}
File:Jagged Array Representation.png
In computer science, a jagged array, also known as a ragged array {{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}} or irregular array {{Cite book |title=Handbook of Data Structures and Applications |publisher=CRC Press |year=2004}} is an array of arrays of which the member arrays can be of different lengths,{{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–}} producing rows of jagged edges when visualized as output. In contrast, two-dimensional arrays are always rectangular{{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}} so jagged arrays should not be confused with multidimensional arrays, but the former is often used to emulate the latter.
Arrays of arrays in languages such as Java, PHP, Python (multidimensional lists), Ruby, C#.NET, Visual Basic.NET, Perl, JavaScript, Objective-C, Swift, and Atlas Autocode are implemented as Iliffe vectors.
Examples
In C# and Java{{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}} jagged arrays can be created with the following code:{{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}}
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
In C and C++, a jagged array can be created (on the stack) using the following code:
int jagged_row0[] = {0,1};
int jagged_row1[] = {1,2,3};
int *jagged[] = { jagged_row0, jagged_row1 };
In C/C++, jagged arrays can also be created (on the heap) with an array of pointers:
int *jagged[5];
jagged[0] = malloc(sizeof(int) * 10);
jagged[1] = malloc(sizeof(int) * 3);
In C++/CLI, jagged array can be created with the code:{{cite web|title=Jagged Arrays|url=http://www.functionx.com/cppcli/arrays/jagged.htm|website=FunctionX|accessdate=26 November 2014}}
using namespace System;
int main()
{
array
//elements
return 0;
}
In Fortran, a jagged array can be created using derived types with allocatable component(s):
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]
In Python, jagged arrays are not native but one can use list comprehensions to create a multi-dimensional list which supports any dimensional matrix:{{cite web|title=Lists in Python Demystified|url=http://alvin.io/lists-in-python-demystified-part-2/|website=Alvin.io|accessdate=31 January 2016}}
multi_list_3d = [[[] for i in range(3)] for i in range(3)]
multi_list_5d = [[[] for i in range(5)] for i in range(5)]