stringBug
Description of the page content
Demo of a Beta BASIC's bug, for Sinclair ZX Spectrum.
While writing the program Alien-B in Beta BASIC 4.0+D, I discovered a bug in the language: The STRING$ function sometimes doesn't work fine if nested. In order to show it, I wrote this little program.
Screenshot
The program shows what the results of some calculations should be, and what they actually are. It shows their code too.
Source code
10 REM stringBug
20 REM A demo of a Beta BASIC 4.0+D's bug, found out by the author
30 REM By Marcos Cruz (programandala.net)
40 REM 2010-11-23 First version
50 REM 2011-02-03 Some little changes in the code
60 RANDOMIZE USR 58419
REM Beta BASIC on
70 WINDOW 0
PAPER 0
BORDER 0
INK 1
CSIZE 8,7
CLS
80 PRINT "Bug in Beta BASIC 4.0+D:"'"sometimes nested STRING$ doesn't"'"work fine."'
90 PRINT INVERSE 1'"Should be","Result"
100 PRINT 300,LEN STRING$(10,"012345678901234567890123456789")
110 PRINT 300,LEN STRING$(10,STRING$(10,"abc"));" (nested)"
120 PRINT 448,LEN STRING$(14,"123456789_123456789_123456789_12")
130 PRINT 448,LEN STRING$(14,(CHAR$(0)+STRING$(28,"a")+CHAR$(0)));" (nested)"
140 PRINT 392,LEN STRING$(28,"123456789_1234")
150 PRINT 392,LEN STRING$(28,STRING$(14,"a"));" (nested)"
160 PRINT 392,LEN STRING$(14,STRING$(28,"a"));" (nested)"
170 PRINT 10,LEN STRING$(5,STRING$(2,"A"));" (nested)"
180 PRINT 10,LEN STRING$(2,STRING$(5,"A"));" (nested)"
190 CSIZE 4,7
PRINT
LIST 100 TO 170
200 CSIZE 8
PAUSE 0
STOP
210 DEF PROC s
220 ERASE d*"stringBug~"
230 ERASE d*"stringBug" TO "stringBug~"
240 SAVE d*"stringBug" LINE 10
250 END PROC
Downloads
The +D disk images contain, beside the program stringBug, the following:
- Beta DOS 1.3 (1990), fixed with the Betafix programs published in Format (number 9/9, 1996-05) and Outlet (number 132, 1998).
- Beta BASIC 4.0+D (1987), for ZX Spectrum 128 with +D interface.
The Autoload program loads both Beta BASIC and the program stringBug.
- stringbug.mgt.zip (49.86 KiB) Zipped +D disk image.
- stringbug.mgt.gz (49.75 KiB) Gzipped +D disk image.