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Part III: Programming Concepts
dynamic array. It assumes that the NumElements variable contains a value,
which your code calculated.
ReDim MyArray (1 To NumElements)
When you redimension an array by using ReDim, you wipe out any values currently
stored in the array elements. You can avoid destroying the old values
by using the Preserve keyword. The following example shows how you can
preserve an array’s values when you redimension the array:
ReDim Preserve MyArray(1 To NumElements)
If MyArray currently has ten elements and you execute the preceding statement
with NumElements equaling 12, the first ten elements remain intact, and
the array has room for two additional elements (up to the number contained
in the variable NumElements). If NumElements equals 7 however, the first
seven elements are retained but the remaining three elements meet their
demise.
The topic of arrays comes up again in Chapter 10, when I discuss looping.
Using Labels
In early versions of BASIC, every line of code required a line number. For
example, if you had written a BASIC program in the ’70s (dressed, of course,
in your bell bottoms), it may have looked something like this:
010: LET X=5
020: LET Y=3
030: LET Z=X*Y
040: PRINT Z
050: END
VBA permits the use of such line numbers, and it even permits text labels. You
don’t typically use a label for each line, but you may occasionally need to use
a label. For example, insert a label if you use a GoTo statement (which I discuss
in Chapter 10). A label must begin with the first nonblank character in a
line and end with a colon.
The information in this chapter becomes clearer as you read subsequent
chapters. If you want to find out more about VBA language elements, I refer
you to the VBA Help system. You can find as much detail as you need, or
care, to know.