Intel Fortran Language Reference - NCI National Facility

B Intel Fortran Language Reference
DEFINE FILE u(m, n, U, asv) [, u(m, n, U, asv)] . . .
u
Is a scalar integer constant or variable that specifies the logical unit number.
m
Is a scalar integer constant or variable that specifies the number of records in the file.
n
Is a scalar integer constant or variable that specifies the length of each record in 16-bit words (2
bytes).
U
Specifies that the file is unformatted (binary); this is the only acceptable entry in this position.
asv
Is a scalar integer variable, called the associated variable of the file. At the end of each direct
access I/O operation, the record number of the next higher numbered record in the file is assigned
to asv. The asv must not be a dummy argument.
Rules and Behavior
The DEFINE FILE statement specifies that a file containing m fixed-length records, each
composed of n 16-bit words, exists (or will exist) on the specified logical unit. The records in the
file are numbered sequentially from 1 through m.
A DEFINE FILE statement does not itself open a file. However, the statement must be executed
before the first direct access I/O statement referring to the specified file. The file is opened when
the I/O statement is executed.
If this I/O statement is a WRITE statement, a direct access sequential file is opened, or created if
necessary.
If the I/O statement is a READ or FIND statement, an existing file is opened, unless the specified
file does not exist. If a file does not exist, an error occurs.
The DEFINE FILE statement establishes the variable asv as the associated variable of a file. At
the end of each direct access I/O operation, the Fortran I/O system places in asv the record number
of the record immediately following the one just read or written.
The associated variable always points to the next sequential record in the file (unless the
associated variable is redefined by an assignment, input, or FIND statement). So, direct access I/O
statements can perform sequential processing on the file by using the associated variable of the file
as the record number specifier.
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