Dynamic arrays

In addition to static arrays, you can also declare dynamic arrays. Unlike static arrays, which have a predetermined number of elements, the number of elements in a dynamic array can be changed at any time. Example:

int anotherArray[]

This declares a dynamic array called anotherArray. Before you can store anything in this array, you need to call the setLength function to set the number of elements that it can contain:

setLength(anotherArray, 12)

You can now use the elements in the dynamic array:

anotherArray[0] = 8
anotherArray[1] = anotherArray[0] * 2  

Like static arrays, the index of the element can range from 0 to the number of elements - 1. The index value 0 corresponds to the first element in the array.

At any time, you can call setLength again to resize the array. The length function always returns the current size of the array:

setLength(anotherArray, 20)
int currentSize = length(anotherArray)  ; returns 20  

Unlike static arrays, dynamic arrays cannot be multi-dimensional. If you need a multi-dimensional array, you can simulate it like this:

; Simulate a 10x10 two-dimensional array
int twoDimArray[]
setLength(twoDimArray, 10 * 10)
; Initialize the element at position [0, 0]
twoDimArray[0 * 10 + 0] = 13
; Initialize the element at position [8, 2]
twoDimArray[8 * 10 + 2] = 14

Also unlike static arrays, it is not possible to copy dynamic arrays with a single assignment. This will compile, but result in the Arrays are not compatible run-time error message:

int a[]
int b[]
setLength(a, 10)
setLength(b, 10)
a = b   ; Generates run-time error message 

Use a loop to copy the individual elements instead.

Notes

• Unlike static arrays, the elements of a dynamic array are zero-initialized by the setLength function.
• As with static arrays, if you try to access elements of the array that are out of range, a run-time error message will be written to the Compiler Messages tool window if the debug compiler directive is defined.
• Dynamic arrays are slightly less efficient than static arrays, so use a static array if possible.

Next: Type compatibility

See Also
Arrays
Types