Introduction to BASIC Arrays

Arrays
An array is a sequence of variables so that each variable is referred with a number called an index (or a subscript).
Each variable in an array is called an indexed variable.
Arrays must be declared by DIM statements.
Example.
`10 DIM A(4)`
makes an array A and indexed variables A(1)，A(2)，A(3) and A(4) available.
An index can be indicated by a numerical expression.
For Example,`
20 LET N=2
30 LET A(N)=10
`
An array declaration can contain a specification of the lower bound of the indices as follows.
`DIM A(0 TO 10)`
Example. A program that makes a frequency distribution table of class width 10.
This Program terminates when a negative number is entered.

    100 DIM m(0 TO 10)
    110 FOR i=0 TO 10
    120    LET m(i)=0
    130 NEXT i
    140 DO
    150    INPUT x
    160    IF x<0 THEN EXIT DO
    170    LET i=INT(x/10)
    180    LET m(i)=m(i)+1
    190 LOOP
    200 PRINT  "marks", "count"
    210 FOR i=0 TO 10
    220    PRINT i*10, m(i)
    230 NEXT i
    240 END