Array of arrays

The declaration of an "array of arrays" is an alternative notation for multidimensional arrays. Instead of dimensioning the elements, a collection of elements is nested. Any nesting depth can be used.

Syntax

<variable name> : ARRAY[<first>] ( OF ARRAY[<next>] )+ OF <data type> ( := <initialization> )? ;

<first> : <first lower index bound>..<first upper index bound>
<next> : <lower index bound>..<upper index bound> // one or more arrays
<data type> : elementary data types | user defined data types | function block types
// (...)+ : One or more further arrays
// (...)? : Optional

Syntax

Declaration:

<variable name> : ARRAY[<dimension>] OF ARRAY[<dimension>] OF <data type> := [<initialization>];

`<variable name>`	Array name Sample: `aCounter`
`<dimension>`	Dimension (lower to upper index limit) Sample: `1..100` A dimension can have any number of indexed elements, determined by the lower and upper index limits. The index limits are integers up to data type DINT.
ARRAY[<dimension>] OF ARRAY[<dimension>] OF ARRAY[<dimension>] OF	Triple nested array Sample: `ARRAY[1..2, 1..3] OF ARRAY[1..3] OF ARRAY[1..5]`
`<data type>`	Data type of the element: Elementary data type User-defined data type Function block
`<initialization>`	Initial values of the array (optional)

Data access:

<variable name>[<index of first array>][<index of next array>][…]

<variable name>

Array name

Sample: aCounter

<index of first array>

Index of the first (outer) arrays

<index of next array>

Index of the next (inner) array

Sample

The variables aPoints and a2Boxes combine the same data elements, but the notation for declaration and data access are different.

PROGRAM MAIN
VAR
    aPoints : ARRAY[1..2,1..3] OF INT := [1,2,3,4,5,6];
    a2Boxes : ARRAY[1..2] OF ARRAY[1..3] OF INT := [ [1, 2, 3], [ 4, 5, 6]];
    a3Boxes : ARRAY[1..2] OF ARRAY[1..3] OF ARRAY[1..4] OF INT := [ [ [1, 2, 3, 4], [5, 6, 7, 8], [9, 10, 11, 12] ], [ [13, 14, 15, 16], [ 17, 18, 19, 20], [21, 22, 23, 24] ] ];
    a4Boxes : ARRAY[1..2] OF ARRAY[1..3] OF ARRAY[1..4] OF ARRAY[1..5] OF INT;
END_VAR

aPoints[1, 2] := 1200;
a2Boxes[1][2] := 1200;