Commodore 128D - Using Arrays; Subscripted Variables

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Using Arrays
You have seen how to use READ-DATA to provide many values for a
variable. But what if you want the computer to remember all the data
in the DATA statement instead of replacing the value of a variable
with the new data? What if you want to be able to recall the third
number, or the second string of characters?
Each time you assign a new value to a variable, the computer erases
the old value in the variable's box in memory and stores the new
value in its place. You can tell the computer to reserve a row of
boxes in memory and store every value that you assign to that varia
ble in your program. This row of boxes is called an array.
Subscripted If the array contains all of the values assigned to
Variables the variable X in the READ-DATA example, it is
called the X array. The first value assigned to X
in the program is named X(1), the second value
is X(2), and so on. These are called subscripted
variables. The numbers in the parentheses are
called subscripts. You can use a variable or a
calculation as a subscript. The following is
another version of the averaging program,
this time using subscripted variables.
5DIMX(5)
10T = 0
15:
20 FOR J = 1TO5
30 READ X(J)
40T = T + X(J)
50 NEXT
55:
60A = T/5
70? "AVERAGE =";A
80 END
85:
90 DATA 5,12,1,34,18
Notice there are not many changes. Line 5 is the
only new statement. It tells the computer to set
aside five storage compartments (25 bytes) in
memory for the X array. Line 30 has been
changed so' that each time the computer exe
cutes the loop, it assigns a value from the DATA
statement to the position in the X array that cor
responds to the loop counter (J). Line 40 calcu-
61 USING C128 MODE-Advanced BASIC Programming