Texas Instruments TI-99/4A - Page 150

EOF-End-of-File Function
EOF (numeric-expression)
The end-of-file function determines if an end-of-file has been
reached on a file stored on an accessory device. The argument
specifies an open file-number (sec ··OPEN"). The argument is the
value obtamed when the numerIc'expressiOIl is evaluated. 'i'he
normal rules for the evaluation of numeric expressions are used
here.
The value the function provides depends on the position of the file.
The values supplied are:
Value Position
o Not end-of-file
+1 Logical end-of-file
-1 Physical end-of-file
A file is positioned
at a logical end-of-file when all records on the
file
have been processed. A file is positioned at a physical eud'of'file
when no more space is available for the file.
This function and the example on the right cannot be used with
cassette tape recorders. Its use with any other accessory devices
will be
more fully explained in their accompanying manuals.
11·130
Examples:
>NEW
>100 OPEN #2:NAME$,SEQUENTIAL
.INTERNAL.INPUT.FIXED
>110 IF EOF(2) THEN 160
>120 REM IF EOF GIVES ZERO
>130 INPUT #2:A,6,C
>140 PRINT A;6;C
>150 GDTD 110
>160 CLOSE #2
>170 END
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