Function: Assigns a value to a variable. BASIC09 does not require the LET statement to assign values but does accept it in order to be compatible with versions of BASIC that do require it.

· The result of the LET expression must be of the same type as, or compatible with, the variable in which it is stored.

· BASIC09's assignment function accepts either = or : = as assignment operators. The : = form helps to distinguish assignment operations from comparisons (test for equality) and is compatible with Pascal programming.

Use BASIC09's assignment function to copy entire arrays or complex data structures to another array or complex data structure. The data structures do not need to be of the same type or shape, but the size of the destination structure must be the same as or larger than the source structure. This means the assignment function can perform unusual type conversions. For example, you can copy a string variable of 80 characters into a one-dimensional array of 80 bytes.

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LET A = 5

REND

Function: Performs the logical NOT function on an integer or byte type number. The operation involves a bit-by-bit logical complement operation of the number you specify. For instance, if value is 188, the logic looks like this:

188 Decimal = 10111100 Binary

NOT 10111100

= 01000011

01000011 Binary = 67 Decimal

LNOT changes each bit in a binary number to its complementary binary value all 1 values become 0 and all 0 values become 1. LNOT returns an integer result; it is not a Boolean operator.

This procedure uses one byte (contained in the variable STORAGE) to indicate the results of eight questions. Each bit in the byte indicates a Yes or No answer (Yes =1 and No = 0). The combination logic of LAND and LNOT masks the byte X so that it affects only the appropriate bit of STORAGE to set it to 0 if the answer is No. LOR sets the appropriate bit to 1 if the answer is Yes. The procedure operates in conjunction with the LXOR sample program.

Returns natural logarithm

REND

BASIC09 Command Reference l 11

Returns base 10 logarithm

PRINT LOG10(A/12)

OEND

LOOP/ENDLOOP

statements)

ENDLOOP

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BASIC09 Command Reference / 11

END

ENDEXIT

ENDLOOP

Sample Program:

This procedure simulates a gambling machine that awards cash returns depending on a random selection of kinds of fruits. You begin with a stake of $25 and win or lose according to random selections of the procedure.

The program uses LOOP/ENDLOOP to keep operating until you run out of cash.

PROCEDURE bandit ODIM FRUIT1,FRUIT2,FRUIT3,STAKE:INTEGER; FRUITC10):STRINGLGJ pSTAKE=2S OPRINT \ PRINT "You have $"; STAKE; " to play with."

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BASIC09 Reference

PROCEDURE questions ODIM QUESTION:STRINGC60J; T:INTEGER; X,STORAGE:HYTE ODIM ANSWER:STRINGf1J OX=1 OFOR T=1 TO 8 DREAD QUESTION OPRINT QUESTION; " (Y/N)? "; OGET *O,ANSWER OPRINT OIF ANSWER="y" OR ANSWER="Y" THEN OSTORAGE=LORCSTORAGE,X) OELSE OSTORAGE=LANDCSTORAGE,LNOTCX)) OEND I F OX=X*2 ONEXT T OPRINT STORAGE ORUN summaryCSTORAGE) REND ODATA "Do you have more than one Color Computer" ODATA "Do you use your Color Computer for games" ODATA "Do you use your Color Computer for word processing" ODATA "Do you use your Color Computer for business applications" ODATA "Do you use your Color Computer at home" ODATA "Do you use your Color Computer at the office" ODATA "Do you use your Color Computer more than two hours a day" ODATA "Do you share your Color Computer with others"

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BASIC09 Command Reference l 11

LXOR Returns logical XOR of two numbers

Syntax: LXOR(valuel, valueZ

Function: Performs the logical XOR function on two-byte, or integer-type, values. For instance, if you LXOR the numbers 5 and 6 the logic is like this:

Decimal 5 = Binary 0101

Decimal 6 = Binary 0110 0101

LXOR 0110

= 0011 = 3 Decimal

If one bit or the other bit in the evaluation is 1, but not both, LXOR returns a result of 1. Otherwise, LXOR returns a

result of 0.
Parameters:
valuel A byte or integer number.
valw2 A byte or integer number.

Examples:

PRINT LXOR(11,12)

PRINT LXOR($20,$FF)

Sample Program:

The following program summarizes the results of the sample program for LOR. The LOR program stored the answers to eight questions in a single byte. This procedure reads the byte and displays appropriate comments. LXOR checks to see if two of the answers are "yes" or "no."

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BASIC09 Reference

pENDEXIT
pPRINT "Your Stake i5 now $"; STAKE; "."
pPRINT
pPRINT
pINPUT "Pre55 ENTER to pull again...",Z$
OENDLOOP
pEND
pDATA "ORANGE","APPLE","CHERRY","LEMON","BANANA"
ODATA "PEAR", "PLUM","PEACH","GRAPE","APRICOT"

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BASIC09 Command Reference l I Z

LOR Returns logical OR of two numbers

Syntax: LOR(valuel, valueZ

Function: Performs the logical OR function on a byte- or integer-type value. The operation involves a bit-by-bit logical OR operation on two values. For instance, if you LOR the numbers 5 and 6, the logic is like this:

Decimal 5 = Binary 0101

Decimal 6 = Binary 0110

0101

OR 0110

= 0111 = 7 Decimal

If one bit or the other bit is 1, LOR returns a result of 1. Otherwise, LOR returns a result of 0.

Parameters:

valuel A byte or integer number.

value2 A byte or integer number.

Examples:

PRINT LOR(11,12)

PRINT LORC$20,$FF)

Sample Program:

This procedure stores the answers to eight "yes" or "no" questions in one byte, named STORAGE. If you answer "yes" to a prompt, the procedure sets a corresponding bit to 1. If you answer "no" to a prompt, the procedure sets a corresponding bit to 0. The procedure uses LOR to set bits to 1 by masking all bits except the one it needs to set. The procedure operates in conjunction with the LXOR sample program.

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BASIC09 Reference

PROCEDURE summary
ODIM T: INTEGER; A,H,X,TEST,TEST2:HYTE; SUMMARY:
STRINGL501
OPARAM STORAGE:HYTE
DA=0 \H=0
OPRINT \ PRINT
OPRINT "The following is a summary of the
questionnaire answers:"
OPRINT
OPRINT "The surveyee: "
OX=1
OFOR T=1 TO 8
OTEST=LANDCSTORAGE,X)
DREAD SUMMARY
OIF TEST>0 THEN
OPR I NT TAHC 1 0) ; SUMMARY
REND I F
OX=X*2
ONEXT T
OIF LANDCSTORAGE,128)>0 THEN
DA =1
REND I F
OIF LANDCSTORAGE,64)>0 THEN
OB =1
REND I F
OTEST2=LXORCA,H)
DI F TEST2=1 THEN
OPRINT "This computer owner either uses the
computer"
OPRINT "more than two hours a day or shares it
with others."
OPRINT "This is a heavy use situation."
OENDIF
OTEST2=LANDCA,H)
DI F TEST2=1 THEN
OPRINT "This computer user uses the computer more
than two" _
OPRINT "hours per day and shares it with others.
This is a"
OPRINT "super heavy use situation."
DENDIF
REND
ODATA "Uses more than one computer"
ODATA "Plays games"

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BASIC09 Command Reference l 11

pDATA "Uses the computer for word proce55ing" pDATA "U5e5 the computer for bu5ine55" ODATA "Keeps a Color Computer at home" ODATA "Keeps a Color Computer at the office" ODATA "Uses the computer more than two hours a day" ODATA "Shares the computer with others"
BASIC09 Reference

MID$ Returns characters from within a string

Syntax: MID$(string,begin,length)

Function: Returns a substring length characters long, beginning at begin. Use MID$ to "take apart" a string consisting of a number of elements.

Parameters:

string A sequence of string type characters or a
string type variable.
begin The position (an integer value) in string of the
first character to retrieve.
length The number of characters you want to retrieve.

Examples:

NAME$ = "JONES, JOHN M."
LASTNAME$ = MID$(NAME$,8,6)
FIRSTNAME$ = MID$(NAME$,1,S)
INITIAL$ = MID$(NAME$,1S,2)

Sample Program:

This procedure reverses a word or phrase you type. MID$ reads each character in your phrase from the end to the beginning.

PROCEDURE reverse ODIM PHRASE:STRING; T,HEGIN:INTEGER OPRINT "Type a word or phrase you want to reverse:"; OPRINT DINPUT PHRASE OHEGIN=LEN(PHRASE) DPRINT "This is how your phrase looks backwards:" OFOR T=BEGIN TO 1 STEP -1 OPRINT MID$(PHRASE,T,1); ONEXT T OPRINT REND

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BASIC09 Command Reference l 11

MOD Returns modulus of a division

Syntax: MOD(numberl,numberZ

Function: Returns the modulus (remainder) of a division. MOD divides numberl by number2 and calculates the remainder. You can use MOD to put a limit on a numeric variable. For instance, regardless of the value of X, MOD(X,3) produces numbers only in the range 0 through 2. MOD(X,5) produces numbers only in the range of 0 through 4.

You can use MOD to cause repeating sequences. For instance, in a loop, MOD(X,3) produces a repeating sequence of 0, 1, 2, where X increases by 1 in each step of the loop.

Parameters:

numberl A byte, integer or real number dividend.

number2 A byte, integer or real number divisor.

Examples:
PRINT MOD(99,S)

r

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BASIC09 Reference

Sample Program:

This procedure uses MOD to execute repeatedly routines that display asterisks on the screen. There are eight subroutines that the MOD function selects over and over through 100 passes.

PROCEDURE 5tardown
pDIM T: INTEGER
OSHELL "TMODE -PAUSE"
pFOR T=1 TO 1 0 0
pON MODCT,8)+1 GOSUB 10,20,30,40,50,60,70,80
ONEXT T
OSHELL "TMODE PAUSE"
pE N D
1 0pPR I NT USING "S1 0"" , "*" RETURN
20pPRINT USING "S10"","**" \ RETURN
300PRINT USING "S10^","***" \ RETURN
40pPRINT USING "S10^","****" \ RETURN
50pPRINT USING "S10"","*****" \ RETURN
60pPRINT USING "S10^","****" \ RETURN
70pPRINT USING "S10^","***" \ RETURN
800PRINT USING "S10^","**" \ RETURN
OEND

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BASIC09 Command Reference l 11

NEXT Causes repetition in a FOR loop

Syntax: FOR variable = init val TO end val [STEP
value]
[procedure statements]
NEXT variable

Function: NEXT forms the bottom end of a FOR/NEXT loop. Any program statements between FOR and NEXT are executed once for each repetition of the loop, from the initial value to end value.

Parameters:
variable Any legal numeric variable name.
init val Any numeric constant or variable.
end val Any numeric constant or variable.
value Any numeric constant or variable.
procedure Procedure lines you want to execute within
statements the loop.
For more information, see FOR/NEXT/STEP.

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BASIC09 Reference

NOT Returns the complement of a value

Syntax: NOT(value)

Function: Returns the logical complement of a Boolean value or expression.

Parameters:
value A Boolean value (True or False), or an expres
sion resulting in a Boolean value.
Examples:

DIM TEST:HOOLEAN
WHILE NOT(TEST) DO
A=A+1
TEST=A=H
ENDWHILE

Sample Program:

This procedure redirects the current directory listing to a file named Dirfile. It then opens Dirfile and reads the contents, displaying each line on the screen. It uses NOT in a WHILE/ENDWHILE loop to make sure that the end of the file has not been reached before trying to read another entry.

PROCEDURE readfile
ODIM A:STRINGL80J
ODIM PATH:HYTE
OSHELL "DIR > dirf ile"
DOPEN #PATH,"dirfile":READ
EWHILE NOT EOF(#PATH) DO
DREAD #PATH,A
OPRINT A
DENDWHILE
OCLOSE #PATH
FEND

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BASIC09 Command Reference l 11

ON ERROR/GOTO

Establishes an error trap

Syntax: ON ERROR [GOTO linenum]

Function: Sets an error trap that transfers control to the specified line number in a procedure. This lets your program recover from an error and continue execution. To use these commands, your program must have at least one numbered line-the line to branch to in the event of an error.

Parameters:

linenum The line to which you want BASIC09 to
branch should an error occur.

Notes:

0 ON ERROR GOTO is effective only with non-fatal, runtime errors. If such an error occurs without a preceding ON ERROR GOTO statement, BASIC09 enters the DEBUG mode. You must specify ON ERROR GOTO before an error occurs.

0 You turn on error trapping by specifying ON ERROR GOTO linenum. You turn off error trapping by specifying ON ERROR without a line number.

~ Use ON ERROR GOTO with the ERR function (that returns the code of the last error) to specify a particular action for a particular error. You can also use ERROR to simulate an error to test error trapping. For more information on this, see ERROR.

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BASIC09 Reference

Examples:

ODIM FILENAME:STRING ODIM PATH: INTEGER 100INPUT "Name of file to create? ",FILENAME DON ERROR GOTO 100 OCREATE #PATH,FILENAME:UPDATE REND 1000PRINT "That file already exi5t5...plea5e choose another name..." OGOTO 1 0 REND

Sample Program:

If you created a directory file with the GET sample program, you can use this procedure to delete files from the original directory using key characters. For instance, you might type XX as key characters. This means that any filename containing the character group XX is deleted. You can select any key characters you wish, but be sure they apply only to files you want to delete.

If you want to delete all the files in the directory, type an asterisk (*) when asked for key characters.

This procedure uses ON ERROR to let the procedure continue, even if a directory entry cannot be deleted if an entry is a subdirectory. Without the ON ERROR function, the procedure would produce an error and cease execution when it tried to delete a subdirectory.

PROCEDURE purge OREM Use caution with this procedure OREM He Sure to Specify key characters OREM that exist only in the files you OREM want to delete!

ODIM PATH: INTEGER -
ODIM NAMEC100):STRING
ODIM WILDCARD:STRING
OX=0
DOPEN #PATH,"dirfile":READ
OWHILE NOTCEOFC#PATH)) DO
OX=X+1
DREAD #PATH,NAMECX)

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BASIC09 Command Reference l 11

pENDWHILE pFOR T=1 TO X pPRINT NAMECT), pNEXT T pINPUT "Wildcard Characters...",WILDCARD pFOR T=1 TO X pON ERROR GOTO 100 pIF SUHSTRCWILDCARD,NAMECT))>0 OR WILDCARD="*" THEN

pPRINT "DELETING pDELETE NAMECT) pEND I F 10ONEXT T pEND

1 00pPR I NT "*Q*Q*QERROR,p"; NAMECT) ;

deleted ...continuing. pGOTO 1 0 pEND

NAMECT); " "

"pcannot be
BASIC09 Reference

ON/GOSUB Jumps to subroutine on a

specified condition

Syntax: ON pos GOSUB linenum [,linenum,...]

Function: Transfers procedure control to the line number located at position pos in the list of line numbers immediately following the GOSUB command. For example, if pos equals 1, BASIC09 branches to the first line number it encounters in the list. If pos equals 2, BASIC09 branches to the second line number it encounters in the list. If pos is greater than the number of items in the list, execution continues with the next command line. To use ON/GOSUB you must have numbered lines to match the line numbers in your list. End the routines accessed by ON/GOSUB with a RETURN statement.

Parameters:

pos An integer value pointing to a line number in
a list of line numbers.
linenum Any numbered line in the procedure.

Examples:

PRINT "You can now: C1) End the program C2) Print
the re5ult5"
PRINT " C3) Try again C4) Start
a new program"
INPUT "Type the letter of your-choice: ",CHOICE
ON CHOICE GOSUH 100, 200, 300, 400

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