Commodore VIC-20 - Page 137

Chapter 4 Advanced BASIC Programming 123
Nearly every program requires some kind of input from the keyboard.
If you are the person operating the computer, you can probably put together
some
INPUT statements that get the required data and process it in your
program. But if someone else
is operating the computer, sooner or later the
wrong key will be pressed or
an incorrect entry will be made. Every comput-
er operator will make mistakes
at some time. You should write programs
that allow for conceivable human errors.
The same
is true for output programming. If you display the results of a
program with a set of
PRINT statements, those results have to be readable
to the person looking at the display. This does not happen by hacking away
at program statements until the output looks a little better; you must give it
some thought while you are writing the program.
Assume that you want to write a program that inputs names and
addresses. You could write a program to do this quickly and easily enough.
113 REM NAME/ADDRESS PROGRAM
213 DIM NM$(2a)JAD'(2a),cs"(2a)JZC'(2a)
21 REM ARRAYS ARE:
22 REM NM.() FOR NAME
23 REM AD$() FOR ADDRESS
24 REM CS.() FOR CITY AND STATE
26 REM ZC.() FOR ZIP/POSTAL CODE
313 FOR 1=1 TO 213
413 INPUT "~jAME:"; NMf( 1)
513 INPUT "ADDRESS:" i ADI< 1)
613 INPUT "CITY J STATE:" i CS$( 1)
713 INPUT "Z I P /POSTAL CODE:" i ZCI( 1)
813 NEXT 1
913 END
Here is an example of how the program would appear on the display.
RUN
NAME:? NAM THANG
ADDRESS:? 2eee CONSTIT
UTION DR.
CITY~ STATE:? CASTRO V
ALLEY~ CA.
?EXTRA IGNORED
ZIP~POSTAL CODE:? 9191
2
NAME:? PETER SILT
ADDRESS:? 20e KNOW PL.
CITY~ STATE:? AMARILLO
~ TEXAS
?EXTRA IGNORED
ZIP~POSTAL CODE:? 6543
:2