Specifications

BASIC Stamp II

Page 226 • BASIC Stamp Programming Manual 1.8 • Parallax, Inc.

For example:

99 decimal

%1010 binary

$FE hex

“A” ASCII code for A (65)

You can assign names to constants using the CON directive. Once cre-

ated, named constants may be used in place of the numbers they rep-

resent. For example:

cheers con 3 ‘ Number of cheers.

FOR count = 1 to cheers

GOSUB makeCheers

...

That code would work exactly the same as the previous FOR/NEXT

loops. The Stamp host software would substitute the number 3 for the

constant name cheers throughout your program. Note that it would

not mess with the label makeCheers, which is not an exact match for

cheers. (Like variable names, labels, and instructions, constant names

are not case sensitive. CHEERS, and ChEErs would all be processed as

identical to cheers.)

Using named constants does not increase the amount of code down-

loaded to the BS2, and it often improves the clarity of the program.

Weeks after a program is written, you may not remember what a par-

ticular number was supposed to represent—using a name may jog your

memory (or simplify the detective work needed to figure it out).

Named constants have another benefit. Suppose the “Three Cheers”

program had to be upgraded to “Five Cheers.” In the original example

you would have to change all of the 3s to 5s. Search and replace would

help, but you might accidentally change some 3s that weren’t num-

bers of cheers, too. A debugging mess! However, if you made smart

use of a named constant; all you would have to do is change 3 to 5 in

one place, the CON directive:

cheers con 5 ‘ Number of cheers.