As we mentioned above integer arrays can have a second dimension as well. This follows the discussion of extending integer arrays to larger than 64 elements. The technique is similar; If a two-dimensional integer array is required, we enclose subscripts within brackets []. The difference here is that subscripts need to be individually enclosed: For example whereas we would address regular array c() defined with DIM c(4,64) with c(x,y) in the case of its integer counterpart we would address it as %c[x][y]. Each x dimension takes one entire array that follows the base array name. For example using %c [x][y] with x=0 to 5 and y= 0 to 63 will use arrays %C(),%D(),%E(),%F(),%G() and %H()

There are also string arrays. The strings in an array differ from simple strings in that they are of fixed length and assignment to them is always Procrustean – chopped off or padded with spaces. Another way of thinking of them is as arrays (with one extra dimension) of single characters. The name of a string array is a standard variable name followed by $, and a string array and a simple string variable cannot have the same name (unlike the case for numbers).

Suppose then, that you want an array a$ of three strings. You must decide how long these strings are to be – let us suppose that 10 characters each is long enough. You then say:

DIM a$(3,10)

(type this in)

This sets up a 3*10 array of characters, but you can also think of each row as being a string:

Table 4 – Representation of a string array

If you give the same number of subscripts (two in this case) as there were dimensions in the DIM statement, then you get a single character; but if you miss the last one out, then you get a fixed length string. So, for instance, a$(2,7) is the 7ᵗʰ character in the string a$(2); using the slicing notation, we could also write this as a$(2)(7). Now type:

a$(2)="1234567890"

and:

PRINT a$(2),a$(2,7)

You get:

1234567890       7

For the last subscript (the one you can miss out), you can also have a slicer, so that for instance:

a$(2,4 TO 8) = a$(2)(4 TO 8) = "45678"

Remember: in a string array, all the strings have the same –fixed– length. The DIM statement has an extra number (the last one) to specify this length. When you write down a subscripted variable for a string array, you can put in an extra number, or a slicer, to correspond with the extra number in the DIM statement. You can have string arrays with no dimensions. Type:

DIM a$(10)

and you will find that a$ behaves just like a string variable, except that it always has length 10, and assignment to it is always Procrustean. Whatever part of the value doesn't fit gets left out.