The Restore Command - Commodore 128D User Manual

You can use as many READ and DATA statements as you need in a
program, but make sure there is enough data in the DATA statements
for the computer to read. Remove one of the numbers from the DATA
statement in the last program and run it again. The computer
responds with ?OUT OF DATA ERROR IN 30. What happened is that
when the computer executed the loop for the fifth time, there was no
data for it to read. That is what the error message is telling you. Put
ting too much into the DATA statement doesn't create a problem
because the computer never realizes the extra data exists.
The RESTORE Command
You can use the RESTORE command in a program to reset the data
pointer to the first piece of data if you need to. Replace the END
statement (line 80) in the program above with:
80 RESTORE
and add:
85 GOTO 10
Now RUN the program. The program will run continuously using the
same DATA statement. NOTE: If the computer gives you an OUT OF
DATA ERROR message, it is because you forgot to replace the num
ber that you removed previously from the DATA statement, so the
data is all used before the READ statement has been executed the
specified number of times.
You can use DATA statements to assign values to string variables.
The same rules apply as for numeric data. Clear the computer's
memory and type the following program:
10FORJ = 1TO3
20 READ A$
30?A$
40 NEXT
50 END
60 DATA COMMODORE,128,COMPUTER
If the READ statement calls for a string variable, you can place let
ters or numbers in the DATA statement. Notice however, that since
the computer is READing a string, numbers will be stored as a string
of characters, not as a value which can be manipulated. Numbers
stored as strings can be printed, but not used in calculations. Also,
you cannot place letters in a DATA statement if the READ statement
calls for a number variable.
60 USING C128 MODE—Advanced BASIC Programming