Here this should help: (taken from the DBC help menus)
ARRAYS
Arrays are going to be a very important part of your future programs. They allow you to store large amounts of data under a single name. You can then access the data by index rather than by name alone.
If you had to write a program that stored each weeks lottery numbers, typing out 52 unique variable names is a lot of work, hard to maintain and quite unnecessary. Arrays allow you to create a special kind of variable that can store more than one item of data. You might start your program like this:
lottery1$="43,76,12,34,12,11"
lottery2$="76,12,34,12,11,44"
lottery3$="12,34,12,02,05,07"
etc..
Two hours later, you realize you could have written it like this:
DIM lottery$(52)
lottery$(1)="43,76,12,34,12,11"
lottery$(2)="76,12,34,12,11,44"
lottery$(3)="12,34,12,02,05,07"
etc..
We declare a string array using the DIM command followed by a name for our array. Like variables, when we use a dollar symbol after the name we instruct the program to use the array to store only strings. We then enclose in brackets how many items of data we wish the array to store. The array can be filled almost like a variable, but you must also provide the position within the array you wish to store your data.
But you then ask yourself what benefits I would have gained using the second approach. If you where also required to print out all 52 lottery numbers to the screen with your first approach you would have to add another 52 statements that printed each variable:
PRINT lottery1$
PRINT lottery2$
PRINT lottery3$
etc..
But if you had used an array, the same example would look like this:
PRINT lottery$(1)
PRINT lottery$(2)
PRINT lottery$(3)
etc..
You will have noticed that by using an array, you no longer have to refer to your data using a unique variable name. You can now point to the data you want using a position number. Accessing data this way has a thousand advantages over trying to access data by variable name alone, as you will discover. One example would be to improve the above like this:
FOR T=1 TO 52
PRINT lottery$(T)
NEXT T
Incredibly the above code replaced 52 PRINT statements with just 3 statements. With the above example, T is incremented from 1 to 52 within a loop that prints out the contents of the array at that position.
Arrays can also store multiple levels of data. At the moment our lottery entries are stored as strings and the numbers are hard to get at. Let's say we wanted to store all six numbers for every lottery week, we would create an array like this:
DIM lottery(52,6)
Without the dollar symbol($), we are declaring the array to store integer numbers instead of strings. You will also notice we have a second number separated by a comma. This means for every array position from 1 to 52, there is a sub-set numbered 1 to 6 in which multiple data can be stored. You can visualize an array as a filing cabinet with large draws numbered 1 to 52. Within each of the 52 draws is a tray with 6 boxes inside. You can store a value in each box. In all you can store 312 (52 x 6) values in this array. You can have up to five dimensions in your array, which means you can create an array as big as (1,2,3,4,5). Be careful when declaring dimensions as large arrays consume large amounts of memory and may reduce overall performance of your program.
Entering data into our new array is elementary:
lottery(1,1)=43
lottery(1,2)=76
lottery(1,3)=12
lottery(1,4)=34
lottery(1,5)=12
lottery(1,6)=11
lottery(2,1)=43
lottery(2,2)=76
lottery(2,3)=12
lottery(2,4)=34
lottery(2,5)=12
lottery(2,6)=11
You are now able to give your program access to much more useful data. Unlike the string approach, you could make your program count how many times a certain number has appeared.
As you have determined, arrays need to be declared as a particular type. You can have an array of integer numbers, real numbers or strings. You cannot have multiple types in the same array, but you can declare new arrays dedicated to holding such data.
