Arrays in Small Basic

vijayeg

20 Jun 2009 3:04 AM

Comments 7

With version 0.5, Small Basic implements native support for arrays. This is a significant change from how arrays were used in v0.4 and so I want to write about the syntax and the functionality of the new arrays.

Any variable can be used as an array – no special declaration or setup is necessary. Arrays are indexed using square brackets.

numbers[1] = "One"
numbers[2] = "Two"
TextWindow.WriteLine(numbers[1])
TextWindow.WriteLine(numbers[2]) 

Arrays can be indexed with either numbers or text. And you can use different types of indexers in the same array.

myarray["one"] = 1
myarray[2300] = "Two thousand three hundred"
myarray["name"] = "Vijaye" 

Arrays can be copied over via simple assignment. Modifying one array doesn’t affect the other array.

first[1] = "Uno"
first[2] = "Dos"
second = first
TextWindow.WriteLine(second[2]) ' prints Dos
second[1] = "One"
TextWindow.WriteLine(second[1]) ' prints One
TextWindow.WriteLine(first[1]) ' prints Uno 

The values in an array are internally maintained as a string with semicolon separated values:

person["Name"] = "Vijaye"
person["Age"] = 30
person["Address"] = "Redmond"
TextWindow.WriteLine(person) 

This prints:

Name=Vijaye;Age=30;Address=Redmond; 

You can remove elements in an array by setting them to an empty text.

myarray[1] = "One"
myarray[2] = "Two"
myarray[3] = "Three"
TextWindow.WriteLine(Array.GetItemCount(myarray)) ' prints 3
myarray[2] = ""
TextWindow.WriteLine(Array.GetItemCount(myarray)) ' prints 2 

And finally, arrays can be multi-dimensional too

people[1]["Name"]["First"] = "Vijaye"
people[1]["Name"]["Last"] = "Raji"
people[2]["Name"]["First"] = "Carl"
people[2]["Name"]["Last"] = "Fredrickson"
TextWindow.WriteLine(people[2]["Name"]) 

This prints:

First=Carl;Last=Fredrickson;

Theoretically, you can have as many dimensions as you want. However, the way they are implemented internally, a two dimensional array is 2 times slower than a single dimension array, and a three dimensional array is 4 times slower than a single dimensional array and so on. So, I’d recommend not overdoing multidimensional arrays.