An array is used to store many similar types of data using a single variable name.

The array should be pictured as a container with many compartments.

The container has one name, but each of the compartments is numbered.

In order to refer to the value stored in a single compartment, we must use the container name

( the variable ) along with the compartment number ( called the index or subscript )

i.e.  An array called numbers could be visualized in memory as follows:

numbers

0123456789
8-612-5-31916-1172

subscript/index ->

element ->

numbers(4) would refer to the value in position 4 of the array called numbers ( it’s –3 here ) numbers(4) is known as a subscripted variable in this situation

The subscripts (indices) for an array are numbered starting at zero, unless you specify otherwise

Arrays are dimensioned by:

i)   using the highest index needed for the array   or

ii)  giving the range of the indices (lowest to highest).

i.e.

dim numbers(10) as integer –  would set aside space for 11 elements in an array called ‘numbers’  (positions 0 – 10)

dim prices(5 to 10) as single – would set aside space for 6 elements in an array called ‘prices”.    Here the compartments would be numbered from 5 to 10.

Filling an array

You can enter elements one at a time by compartment number like this:     num(1)=3                                                                                                                                                       nam(5)=”Fred”

Or Because the name stays the same and only the index changes,

we can use a For / Next  loop to enter all of the elements in an array.

i.e.       for x = 1 to 10                                                                       for x = 1 to 10

input ”Enter a number”, num(x)                                     num(x) = int(rnd* 100 ) + 1

next x                                                                                                    next x

The 1st structure allows the user to enter 10 different values and have them stored in separate compartments numbered 1 –10, while the other uses random numbers for elements of the array.

Without an array, you can only store one value at a time under the variable num

Whenever we need to access the items in the array, we would again use a for/next loop.

i.e.

for a = 1 to 10
total = total  + num(a)
print num(a);
next a
print
print “The total of all the values is “; total

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