Commodore 1541-II - Writing File Data: Print

EXAMPLE:
If you are writing a grading program, it would be convenient to simply tack on each
student's new grades to the end of their existing grade files. To add data to the "JOHN
PAUL JONES" file, we could type
OPEN 1,8,3,"0:JOHN PAUL JONES,A"
In this case, DOS will allocate at least one more sector (block) to the file the first
time you append to it, even if you only add one character of information. You may also
notice that using the Collect or Validate command didn't correct the file size. On the other
hand, your data is quite safe, and if the wasted space becomes a problem, you can easily
-correct it by copying the file to the same diskette or a different one, and scratching the
original file. Here's a sequence of commands that will copy such files to the original
diskette under the original name, for ease of continued use:
BASIC 2:
PRINT#15,"R0:TEMP = JOHN PAUL JONES"
PRINT#15,<tC0:JOHN PAUL JONES=TEMFf
PRINT#15,"S0:TEMP"
BASIC 3.5:
RENAME "JOHN PAUL JONES" TO "TEMP"
COPY "TEMP" TO "JOHN PAUL JONES"
SCRATCH "TEMP"
If you are using Basic 2, be sure to open file 15 to the command channel beforehand (i.e.,
with OPEN 15,8,15) and close it afterwards (i.e., with CLOSE 15).
WRITING FILE DATA: USING PRINT#
After a sequential file has been opened to write (with a type and direction of
",S,W"), we use the Print# command to send data to it for storage on diskette. If you are
familiar with Basic's Print statement, you will find Print# works exactly the same way,
except that the list of items following the command word is sent to a particular file,
instead of automatically appearing on the screen. Even the formatting options (punctua
tion and such) work in much the same way as in Print statements. This means you have to
be sure the items sent make sense to the particular file and device used.
For instance, a comma between variables in a Print statement acts as a separator in
screen displays, making each successive item appear in the next preset display field
(typically at the next column whose number is evenly divisible by 10). If the same comma
is included between variables going to a disk file, it will again act as a separator, again
inserting extra spaces into the data. This time, however, it is inappropriate, as the extra
spaces are simply wasted on the diskette, and may create more problems when reading the
file back into the computer. Therefore, you are urged to follow the following format
precisely when sending data to a disk file.
FORMAT FOR THE PRINT # STATEMENT
PRINT#file#,data list
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