ioinit.3f

<B>Digital的Unix操作系统VAX 4.2源码</B>

.\" SCCSID: @(#)ioinit.3f	8.1	9/11/90
.TH ioinit 3f VAX "" Unsupported
.SH Name
ioinit \- change f77 I/O initialization
.SH Syntax
\fBlogical function ioinit (cctl, bzro, apnd, prefix, vrbose)\fP
.br
.B logical cctl, bzro, apnd, vrbose
.br
.B character*(*) prefix
.SH Description
.NXR "ioinit subroutine (FORTRAN)"
.NXR "f77 compiler" "initializing I/O system"
This routine will initialize several global parameters in the f77 I/O system,
and attach externally defined files to logical units at run time.
The effect of the flag arguments applies to logical units opened after
.PN ioinit
is called.
The exception is the preassigned units, 5 and 6, to which
.I cctl
and
.I bzro
will apply at any time.
The
.PN ioinit
routine is written in FORTRAN-77.
.PP
By default,
carriage control is not recognized on any logical unit. If
.I cctl
is
.B .true.
then carriage control will be recognized on formatted output
to all logical units except unit 0, the diagnostic channel.
Otherwise the default will be restored.
.PP
By default, trailing and embedded blanks in input data fields
are ignored. If
.I bzro
is
.B .true.
then such blanks will be treated as zeros.
Otherwise the default will be restored.
.PP
By default, all files opened for sequential access are positioned at
their beginning.
It is sometimes necessary or convenient to open at the END-OF-FILE
so that a write will append to the existing data.
If
.I apnd
is
.B .true.
then files opened subsequently on any logical unit
will be positioned at their end upon opening.
A value of
.B .false.
will restore the default behavior.
.PP
The
.PN ioinit
routine may be used to associate file names with FORTRAN
logical unit numbers through environment variables.  See
the ``Introduction to the f77 I/O Library'' in the
.I "ULTRIX Supplementary Documents"
for a more general way of doing this.  If the argument
.I prefix
is a non-blank string, then names of the form
.BR prefix NN
will be sought in the program environment. The value associated with
each such name found will be used to open logical unit NN for formatted
sequential access.
For example, if f77 program
.I myprogram
included the call:
.EX
call ioinit (.true., .false., .false., FORT, .false.)
.EE
then the following sequence:
.EX
% setenv FORT01 mydata
% setenv FORT12 myresults
% myprogram
.EE
would result in logical unit 1 opened to file
.I mydata
and logical unit 12 opened to file
.I myresults .
Both files would be positioned at their beginning.
Any formatted output would have column 1 removed and interpreted
as carriage control.
Embedded and trailing blanks would be ignored on input.
.PP
If the argument
.I vrbose
is
.B .true.
then
.PN ioinit
will report on its activity.
.PP
The effect of:
.EX
call ioinit (.true., .true., .false., , .false.)
.EE
can be achieved without the actual call by including ``\-lI66''
on the
.PN f77
command line.
This gives carriage control on all logical units except 0,
causes files to be opened at their beginning, and causes
blanks to be interpreted as zero's.
.PP
The internal flags are stored in a labeled common block with the following
definition:
.EX
integer*2 ieof, ictl, ibzr
common /ioiflg/ ieof, ictl, ibzr
.EE
.SH Restrictions
.NXR "ioinit subroutine (FORTRAN)" "restrictions"
The
.I prefix
argument can be no longer than 30 characters.  A pathname
associated with an environment name can be no longer
than 255 characters.
.PP
The ``+'' carriage control does not work.
.SH Files
.ta \w'/usr/ucb/lib/libI77.a   'u
.ie \nM /usr/ucb/lib/libI77.a	f77 I/O library
.el /usr/lib/libI77.a	f77 I/O library
.br
.ie \nM /usr/ucb/lib/libI66.a	Sets older FORTRAN I/O modes
.el /usr/lib/libI66.a	Sets older FORTRAN I/O modes
.SH See Also
getarg(3f), getenv(3f)
.br
``Introduction to the f77 I/O Library,''
.I ULTRIX Supplementary Documents,
.br
Vol. II: Programmer