Page 39 - Excel for Scientists and Engineers: Numerical Methods

16 EXCEL: NUMERICAL METHODS

K=K+1

which, in the second example, says "Store, in the memory location to which the
user has assigned the label 'K, the value corresponding to the expression K + 1 .I'
Operators

VBA operators include the arithmetic operators (+, -, *, /, "), the text
concatenation operator (a), the comparison operators (=, c, >, c=, >=, c>) and
the logical operators (And, Or, Not)

Variables
Variables are the names you create to indicate the storage locations of values
or references. There are a few rules for naming variables or arguments:
You can't use any of the VBA reserved words, such as Formula,
Function, Range or Value.
The first character must be a letter.
A name cannot contain a space or a period.
The characters %, $, #, !, & cannot be embedded in a name. If one of
these characters is the last character of a variable name, the character
serves as a type-declaration character (see later).
You can use upper- and lowercase letters. If you declare a variable type
by using the Dim statement (see "VBA Data Types'' later in this chapter),
the capitalization of the variable name will be "fixed" - no matter how
you type it in the procedure, the variable name will revert to the
capitalization as originally declared. In contrast, if you have not declared
a variable by using Dim, changing the case of a variable name in any line
of code (e.g., from formulastring to Formulastring) will cause all instances
of the old form of the variable to change to the new form.
You should make variable names as descriptive as possible, but avoid overly
long names which are tedious to type. You can use the underscore character to
indicate a space between words (e.g., formula-string). You can't use a period to
indicate a space, since VBA reserves the period character for use with objects.
The most popular form for variable names uses upper- and lowercase letters
(e.g., FormulaString).
Long variable names like Formulastring provide valuable self-
documentation; months later, if you examine your code in order to make
changes, you'll probably be more able to understand it if you used (for example)
Formulastring as a variable name instead of F. But typing long variable names is
time-consuming and prone to errors. I like to use short names like F when I'm
developing the code. Once I'm done, I use the Visual Basic Editor's Replace ...
menu command to convert all those F's to Formulastring.