Introduction to BASIC
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.
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.
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