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BSD 4.3tahoe

.TI F77/IO_RANDOM "Sep. 15, 1984"
Random Access I/O

F77 allows files to be accessed by both sequential and direct (random)
access reads and writes.
For example, suppose you want
to use random access I/O on unit 10 with records that are 20 bytes
long.
Open unit 10 by:

.nf
	open(10, file='randfile', form='unformatted',
       .	access='direct', recl=20 )
.fi

Write to it by:

.nf
	real vec(5)
	   ...
	write(10, rec=n) vec
.fi

and read from it by:

	read(10, rec=n) vec

where n contains the record number being read or written.
The f77 I/O library
keeps track of the highest record number written to the file.
Any time
a write specifies a higher record number, the file is extended.
If a
read specifies a higher record number, an end-of-file error results.
Records not explicitly written contain zeros.

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