Defining An Array; Dim Statement For One-Dimensional Arrays - IBM 5110 Basic Introduction

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The second example is really a modified combination of the three one-

dimensional arrays. The first column has been changed to the numeric

representation of the months because the names of the months

(character data) cannot be included in the same array with numeric

data.

It will be much easier to use the weather data if we keep it together in

three one-dimensional arrays, or in one two-dimensional array, than it

would be if we considered it as 36 separate variables. This chapter

will show you how to work with arrays in BASIC programs.

DEFINING AN ARRAY

When you want to work with an array, you must first tell the system

that you are using an array and not ordinary variables. This is called

defining your array. Defining the array merely involves telling the

system how big the array is going to be so the system can leave room

for it, and telling the system what kind of data will be in it. (Later on

you enter the data, but this is not part of defining the array.)

The data for your arrays can be numeric data or character data. You

can define an array to contain either kind of data, but it must contain

only one kind of data. You can't mix characters and numbers in a

single array. That's why we used the numbers of the months instead

of their names when we put the weather data in a two-dimensional

array.

An array composed of numbers is called an arithmetic array. It is

named by a single letter of the extended alphabet such as A or

An array composed of character data is called a character array. It is

named by a single letter of the extended alphabet followed by a dollar

sign ($); for example, N$ or Q$.

To define either kind of array, you use a statement called DIM. In the

DIM statement, you name the array and include the size of it in

parentheses after the name.

DIM Statement for One-Dimensional Arrays

For a one-dimensional array, the size is a single number. Thus, to

define an arithmetic one-dimensional array A with 12 elements, your

DIM statement is:

0010 DIM A(12)

Arrays