Arrays are used to store sequences of variables, or elements. An element within an array is accessed by indexing the array with an integer offset.
The general syntax for indexing an array is:
ArrayExpression [ index1 , index2 etc... ]
The most common way to create an array is when declaring a variable:
This will initialize the int_array variable with a 10 element array. You can declare an empty array by using :
An empty array is identical to an array with 0 elements.
Arrays may also be created 'on the fly' using the syntax:
New [ Dimension1 , Dimension2 etc... ]
This returns an array of the specified dimension(s) with each element initialized to Null. For example:
Local int_array:Int int_array = New Int
Auto arrays may be created using the syntax:
[ Element1 , Element2 etc... ]
This returns a one dimensional array containing the specified elements, for example:
Local int_array = [1,2,3,4,5]
Each element of an auto array must have exactly the same type. If necessary, you can use type conversions to enforce this.
Here are some examples of using array methods:
Strict Local arr:String = ["some", "random", "strings", "in", "a", "string", "array"] arr.Sort ' sort ascending Print "Array in ascending order..." For Local t:String=EachIn arr Print t Next arr.Sort False 'sort descending Print "Array in descending order..." For Local t:String = EachIn arr Print t Next Local arr2[10,20,30,40] 'Dump array dimensions For Local i = EachIn arr2.Dimensions() Print i Next
Copying an Array
Since arrays are objects, the following code does not actually copy the array, but rather creates another variable that references the same object.
Local arr:Int = [1,2,3] Local arr2:Int = arr
To copy an array, you must use slices. The syntax for slicing is
array[from..to]. Both from and to may
be omitted; they default to 0 and the last index, respectively. Copying the array is simple:
Local arr2:Int = arr[..]
Resizing an array using slices:
Local myArray ' Create an array with 10 elements (0..9) myArray = myArray[..20] ' Increase number of elements in the array to 20 myArray = myArray[..5] ' Take the first 5 elements
Note that you cannot use slices with multi-dimensional arrays.
Resizing an Array of Arrays
Note: this is a slightly advanced topic which may confuse beginners.
Although you cannot resize normal multi-dimensional arrays, you can resize an array of arrays (that being a 1D array where each element is a 1D array).
You first need to resize the main array and then loop through each element in it and resize the arrays that they contain.
Local x :Int ' Create our array of arrays x = x[ .. 5 ] ' resize the main array to have 5 elements ' loop through each new element in this array ' and resize the arrays that they contain For l = 0 Until Len( X ) x[ l ] = X[ l ][ .. 5 ] Next
To create an array with more than one dimension, you can specify indexes separated by commas:
Local int_array1 : Int[4,4] 'create a 4x4 array Local int_array2 : Int[3,3,3] 'create a 3x3x3 array You can then refer to them like so: int_array1[0,0] = 100 int_array2[2,1,0] = 1000
Multi-Dimensional Auto Arrays
Note: this is a slightly more advanced topic and as such, beginners may find it confusing.
It is not currently possible to create normal multi-dimensional arrays AND auto-initialize them.
You can however cheat a little:
Local string_array:String = [["Bob","Kate","Percy"],["Cecil","Edmund","Elizabeth"]] Print string_array 'this will print Percy Print string_array 'this will print Cecil
What the above actually does is create an array of type String Array. If you were to attempt to refer to it in the conventional manner it would cause an error (Incorrect number of array dimensions).
Local string_array:String = [["Bob","Kate","Percy"],["Cecil","Edmund","Elizabeth"]] Print string_array[0,0] 'this line would cause an error
Arrays provide a Sort method, a Dimensions method and a read-only length field. In addition, there are three other fields which you may find of some use.
Method Sort(ascending:Int = True)
Takes an optional ascending parameter that defaults to true. Here is an example of sorting an array:
Strict Local arr:String=["some","random","strings","in","a","string","array"] arr.Sort 'sort ascending Print "Array in ascending order..." For Local t:String=EachIn arr Print t Next arr.Sort False 'sort descending Print "Array in descending order..." For Local t:String=EachIn arr Print t Next
Returns an int array with array dimensions.
So for example
Int[10,5].Dimensions() would return
Int equal to the auto array
Returns an Int value indicating the number of dimensions in the array.
Field elementTypeEncoding:Byte Ptr
Byte Ptr to a value representing the data type of the array elements.
Type encoding will return one of the following: TYPE_BYTE, TYPE_SHORT, TYPE_INT, TYPE_FLOAT, TYPE_LONG, TYPE_DOUBLE, TYPE_STRING, TYPE_OBJECT, TYPE_ARRAY, TYPE_POINTER.
Returns an Int value, the number of elements * the size of the element type.
Local a:Int[2,2,2] Print a.numberOfDimensions ' Prints 3 Print a.elementTypeEncoding ' Prints 105 if Int, 102 if Float, 36 if String Print a.sizeMinusHeader
Iterating through Array Elements
' create a 10 element array and pre-initialize the values Global myArray:Int = [0,1,2,3,4,5,6,7,8,9] For Local i:Int = EachIn myArray ' print the int contained in each array element Print i Next
This is all very well, but what if you want to only loop through a portion of them? Say for instance, the last five. Well for that, you need a slice like so:
' create a 10 element array and pre-initialize the values Global myArray:Int = [0,1,2,3,4,5,6,7,8,9] ' loop through each element starting with the sixth element (0 based array index) For Local i:Int = EachIn myArray[5..] ' print the int contained in each array element Print i Next