Commodore Plus 4 - Page 17

The Elements of BASIC 8
Variable Names
Variable names can be one letter followed by other letters or numbers, plus either
% or $ when appropriate. Note, however, that although longer variable names are
accepted, BASIC reads only the first two characters (plus $ or %) in any variable
name. Additional characters are ignored; use them only to make your program
more readable. Because BASIC reads only the first two characters, make sure all
variables in a program have unique names for the first two characters. In other
words, do not use COMPANYS and COUNTRYS as variables in the same
program unless you want them to have the same value.
Also be sure that variable names do not contain any BASIC keywords. If this
occurs, the program aborts in a SYNTAX ERROR. For example, do not use a
variable such as WORDEF, which contains the keyword DEF. Keywords cannot
appear in variable names even if they are not the first two characters.
Using Variables in Parameters
Note that in most cases a variable can be used in place of a number or text string in
a command parameter. The variable must, of course, be the right type of variable.
You can generally use a calculation in place of a number or numeric variable in a
command parameter. For example, any of the following forms is legal:
FOR X = 1 TO 5
FOR X = 1 TO A
FOR X = A TO B-l
Arithmetic Operators
Table 1-2 shows the operators that are used for solving mathematical problems.
Note that the multiplication symbol is an *, not an x, and that the exponentiation
symbol is an up arrow.
Table 1-2. Mathematical Operators
t Exponentiation
* Multiplication
/ Division
+ Addition
Subtraction and negation