i want to create new file at each loop, i don't know how to do...
!file1, file2,....., file[n]
OPEN (1,FILE='file1.out',ACCESS='SEQUENTIAL',STATUS='UNKNOWN')
do ph=1,N6
do i=1,nx-1
A(i)=mu*U(i-1)
end do
do j=0,nx
U(j)=A(j)
end do
if (mod(ph,Ne)==0) then ! ?
WRITE(1,200) nt,U(i)
endif
200 format(5E12.4)
end do
Or maybe, i can write with a newline or column ?
I'm a beginner in fortran.
Thanks
Your existing code should output more than just last write statement to the file ... it is a sequential file, which means that the output is added to the file in sequential order. If you are only seeing one output, perhaps that is all that the IF statement is causing to be output?
If you still wish to output to multiple files, the easiest way to output to multiple files is to reuse the unit number and have the program create filenames. You need to close the file / unit and reopen it. This is much more easier than have multiple open statements and unit numbers, which would quickly become awkward as the number of files increased. Here is a code fragment that assumes fewer than 100 files:
do i=1, N
write (filename, '("myfile", I2.2, ".txt")' ) I
open (file=filename,unit=16,...)
calculations...
write (16,'(5E12.4)') nt,U(i)
close (16)
end do
Related
I have a Fortran program that needs to read ASCII files, however the list of files sometimes includes a file of size 0. The program then crashes when trying to read this file. I have not find any way so far that will allow me to flag such a file.
I have following READ statement in my code
read(10,220,END=320,ERR=195)parm(1:)
although I expect code to go to statement 195, or to statement 320, without crashing, it crashes
this is where the code crashes when the file size is zero, with the following messages
...
fmt: end of file
apparent state: unit 10 named junko.con
last format: (A)
lately reading sequential formatted external IO
I tried using the INQUIRE statement
inquire (unit=10,SIZE=nsize), but the program would not compile
the OPEN statement did not give any error when opening the zero size file, and the values of IOSTAT was the same, irrespective of the file size
As Ian noted, any modern Fortran compiler should have INQUIRE. A simple test of
program foo
integer sz
inquire(file='tmp.dat',size=sz)
print *, sz
end program foo
with an empty tmp.dat file sets sz=0.
I just want to know that how to retrieve all the record from universe database table using universe basic subroutine.I am new in universe.
Perhaps something like this in the unibasic
OPEN "filename" to FIL ELSE STOP 201,"cannot open filename"
EXECUTE "SELECT filename"
LOOP WHILE READNEXT ID
READ REC FROM FIL,ID ELSE REC = ""
* you now have the entire row in REC
REPEAT
Can you provide more information on what you are trying to do?
Having a subroutine call return the entire contents of a UniVerse file could return a large amount of data. I would expect you would be better off only returning a subset of the items so the calling routine can process a bit at a time.
New content based on comment:
Ok, since you mentioned a type 19 file, I assume you want to read one file from the directory/folder the file points to.
In your subroutine, you can use OPEN on the type 19 file, and use the READ command to read the file. ( Note that you can also use READU, READL, MATREAD, MATREADU, or MATREADL to get the entire file in the directory/folder, depending on if/how you want to lock the item and if you want the data in a dynamic or dimensioned array. If you only need a specific attribute you can then use READV, READVL or READVU commands.
Or, since this is a type 19 file, you can use sequential reads. Open the file with OPENSEQ and read with the READSEQ or READBLK command.
There is an article and sample code on GitHub on how to execute U2 UniVerse Subroutine.
Execute Rocket MV U2 Subroutine Asynchronously using C# (async\await) and U2 Toolkit for .NET. Convert Subroutine Multi-Value Output to Json/Objects/DataTable
These sample code are based on C# (async\await), but you can use for synchronous programming as well with little code tweak.
For article:
Go to this link :
https://github.com/RocketSoftware/multivalue-lab/tree/master/U2/Demos/U2-Toolkit/AsyncAwait/Execute_Subroutine_Async
Read ‘Subroutine-Async.docx’ file.
Sample Code for this article on GitHub
Go to this link :
https://github.com/RocketSoftware/multivalue-lab/tree/master/U2/Demos/U2-Toolkit/AsyncAwait/Execute_Subroutine_Async
OPEN '',FILENAME TO F.FILE ELSE STOP
SELECT F.FILE
LOOP
READNEXT K.FILE ELSE EXIT
READ R.FILE FROM F.FILE, K.FILE ELSE NULL
PRINT R.FILE
REPEAT
PRINT "All over Red Rover"
Filename should be in quotes, i.e "MYFILE" or 'MYFILE'
The loop will repeat till all records have been read and will then exit.
My program works with a set of files (several millions). All the files were created earlier with some other code. Some of the files are empty, some have values; all of them have 'OLD' status. My program has to
open one of the files;
add some value to the END of THE FILE if the file contains numbers already or just put a first value if the file is empty;
close the file and go to another file processing.
Right now, if the file is non-empty, the program erase the file's previous content and just write a new value. I think, in order TO ADD a value to the end of existing non-empty file I need to use some clause in OPEN or WRITE statement in addition to the 'OLD' status. Which ones? Thank you.
It would be easier with a MWE, but nonetheless, what you could do is something like that, using the append keyword
open(unit=file_unit, file=filename, status='old', access='append')
You could try it on this simple example adapted from the Fortran Wikibook to see how it works
program write
implicit none
integer :: i, j
integer, parameter :: out_unit=10
print*,"Enter two integers:"
read (*,*) i, j
open (unit=out_unit, file="results.txt", action="write", status="old", access="append")
write (out_unit,*) "The product of",i," and",j
write (out_unit,*) "is",i*j
close (out_unit)
end program write
Folks,
we collect large amounts of data and create error, status, info log files to let us know what's
going on. We use ofstreams to write to these files. After some period of time (days), we get a
file error (indicated by .good() call) on one of the ofstreams. In the affected log file, it
appears that the write of a single line begins but is interrupted by a write of the exact same
line. For example,
### Random Line of Text 1 ###
### Random Line of Text 2 ###
### Random Line of Text 3### Random Line of Text 3 ###
Each file/ofstream has a single thread that does the actual writing. We don't flush for performance
reasons and shouldn't have to.
Its always the same type of error.
It does only happen on one of three machines running the same code but we don't see any I/O errors
but maybe not looking in the right place.
Thanks for you time.
I would like to know if in Fortran it is possible to use just a single command (with options/specifiers) to do the following:
open a file if it exists and append some data
(this can be done with: open(unit=40,file='data.data',Access = 'append',Status='old') but if the file does not exist a runtime error is issued)
create the file if it does not exist and write some data.
I am currently using inquire to check whether the file exist or not but then I still have to use the open statement to append or write data.
As far as I am aware of, the only safe solution is to do the way you're already doing it, using different open statements for the different cases:
program proba
implicit none
logical :: exist
inquire(file="test.txt", exist=exist)
if (exist) then
open(12, file="test.txt", status="old", position="append", action="write")
else
open(12, file="test.txt", status="new", action="write")
end if
write(12, *) "SOME TEXT"
close(12)
end program proba
You may be interested in my Fortran interface library to libc file system calls (modFileSys), which could at least spare you the logical variable and the inquire statement by querying the file status directly:
if (file_exists("test.txt")) then
...
else
...
end if
but of course you can program a similar function easily yourself, and especially it won't save you from the two open statements...
open(61,file='data.txt',action='write',position='append')
write(61,*) 'hey'
close(61)
This will append to an existing file, otherwise create and write. Adding status='unknown' would be equivalent.
if you replace the status from 'old' to 'unknown' then you will not get the run time error if the file exists or now.
Thanks
In open statement add the attribute access as follows;
Open(unit=031,file='filename.dat',form='formatted',status='unknown',access='append')
The above statement will open the file without destroying old data and write command will append the new lines in the file.
The simplest solution for fortran 90.