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where "file #" is the same file number given in the desired file's current Open statement.
During any given access of a particular file, the file number must remain constant because
it serves as a shorthand way of relating all other file-handling commands back to the
correct Open statement. Given a file number, the computer can look up everything else
about a file that matters.
The "data list" is the same as for a Print statement - a list of constants, variables
and/or expressions, including numbers, strings or both. However, it is strongly recom
mended that each Print# statement to disk include only one data item. If you wish to
include more items, they must be separated by a carriage return character, not a comma.
Semicolons are permitted, but not recorded in the file, and do not result in any added
spaces in the file. Use them to separate items in the list that might otherwise be confused,
such as a string variable immediately following a numeric variable.
Note: Do not leave a space between PRINT and #, and do not abbreviate the
command as ?#. The correct abbreviation for Print# is pR.
EXAMPLES:
To record a few grades for John Paul Jones, using a sequential disk file #1 previously
opened for writing, we could use:
200 FOR CLASS = 1 TO COURSES
210: PRINT#1,GRADE$(CLASS)
220 NEXT CLASS
320 GOSUB 59990:REM CHECK FOR DISK ERRORS
(assuming your program includes an error check subroutine like the one in the last
chapter).
In using Print# there is an exception to the requirement to check for disk
errors after every file-handling statement. When using Print#, a single check after
an entire set of data has been written will still detect the error, so long as the check
is made before any other file-handling statement or disk command is used. You
may be familiar with Print statements in which several items follow each other:
400 PRINT NAME$,STREET$,CITY$
To get those same variables onto sequential disk file number 5 instead of the screen, the
best approach would be to use three separate Print# statements, as follows:
400 PRINT#5,NAME$
410PRBSfT#5,STREET$
420PRINT#5,CITY$
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