I'm trying to create the full path of a file, entering the parent folder in via a Read statement:
PROGRAM fileTest
IMPLICIT NONE
Character(LEN=20) :: dirpath,fullpath
Write(6,*) 'Enter dir path'
Read(*,'(a)') dirpath
dirpath=TRIM(dirpath)
fullpath=dirpath//'/file.abc'
print*,fullpath
END PROGRAM fileTest
Using gfortran, the code compiles, but entering /home/chris results in the final print statement still giving
/home/chris /file.abc
(note the 9 characters of whitespace).
How do I get rid of the spurious whitespaces?!
This happens because dirpath is still a character(len=20) variable, so its contents are again padded with spaces after dirpath=TRIM(dirpath). You have to do the trimming like this:
fullpath = trim(dirpath)//'/file.abc'
Edit:
As a demonstration of allocatable strings (see my comment), you should be able to handle arbitrary string length more satisfactorily like such, provided your compiler supports this feature:
character(:), allocatable :: fullpath
character(len=some_length) :: buffer
write(6,*) 'Enter dir path'
read(*,'(a)') buffer
fullpath = trim(buffer) // '/file.abc'
The string fullpath should be automatically allocated to accommodate the exact length of the right-hand side.
Related
I would like to read the same line of a file many time in Fortran. The concerned data are real values. I tried to build this code as test but I am always getting it wrong.
program advance
implicit none
integer , parameter :: ut = 20
character(len=7) :: fname = 'dat.dat'
integer :: n, idx
character(len=100) :: lnumber
open(unit = ut, file =fname, status='old', action='read')
n = 10
do idx = 1, n
read(ut, '(a)', advance = 'no') lnumber
print *, lnumber
end do
end program advance
The dat.dat file contains one line with 25.325654515464564564
The code return the following error.
At line 13 of file advance.f90 (unit = 20, file = 'dat.dat')
Fortran runtime error: End of record
How do I fix this bug?
Such non-advancing input (using advance='no') doesn't mean that the file position is not advanced at all. It means that the file position isn't advanced beyond what is needed to satisfy the requirements of the input list.
So, in this case, the file position is advanced by reading the single "real number" into the character variable lnumber. The next read will continue from this later point. This later point happens to be the end of the file.
With advancing input more generally, the file position is advanced to the start of the next record even if the record is not required in entirety.
As High Performance Mark comments, reading the same line over and over again likely isn't what you should be doing. You could read the line into a character variable (such as is done here) and repeatedly use that variable as an internal file. However, if you really want to read a line again, consider backspace.
I create a fortran code to calculate the temperature of a cfd model. This code will be called on every iteration of a steady state simulation and calculate the temperature. On every calling of my code/iteration i want my fortran code also save the temperature field on a txt file and save. After calculating the temperature field and saving the values in TFIELD(100;1:6) the part with saving in txt file looks like:
OPEN(UNIT=35,FILE='W:\temperaturField.txt',
&FORM ='FORMATTED',STATUS='UNKNOWN',
&ACTION='READWRITE')
WRITE (35,FMT='5(F8.3,2X))') TFIELD(100,1:6)
With this code it only overwrites the first line of my txt file on every iteration. But i want to paste every TFIELD(100,1:6) array on a new line. How can i do this?
Add POSTITION='APPEND' to the OPEN:
OPEN(UNIT=35,FILE='W:\temperaturField.txt',
&FORM ='FORMATTED',STATUS='UNKNOWN',POSITION='APPEND',
&ACTION='READWRITE')
It seems like you are opening and closing the file for each iteration. This is a quick and dirty method if you need to debug, but it's slow.
If you want to do that, you might want to do what #Jack said: Include a POSITION='APPEND' to the OPEN statement to set the position to write the data to the end of the file. Also, you need to make sure that you close it every time.
A better (more efficient) method would be to keep the file open for the whole time. I'd do that with a module:
module temp_writer_module
implicit none
integer :: temp_writer_unit
logical :: is_opened = .FALSE.
private :: temp_writer_unit, is_opened
contains
subroutine temp_writer_open()
integer :: ios
character(len=100) :: iomsg
if (is_opened) then
print*, "Warning: Temperature file already openend"
return
end if
open(newunit=temp_writer_unit, file='W:\temperatureField', &
form='FORMATTED', status='UNKNOWN', action='WRITE', &
iostat=ios, iomsg=iomsg)
if (ios /= 0) then
print*, "Error opening temperature file:"
print*, trim(iomsg)
STOP
end if
is_opened = .TRUE.
end subroutine temp_writer_open
subroutine temp_writer_close()
if (.not. is_opened) return
close(temp_writer_unit)
is_opened = .FALSE.
end subroutine temp_writer_close
subroutine temp_writer(temps)
real, intent(in) :: temps(6)
integer :: ios
character(len=100) :: iomsg
if (.not. is_opened) call temp_writer_open()
write(temp_writer_unit, *, iostat=ios, iomsg=iomsg) temps
if (ios /= 0) then
print*, "Error writing to temperature file:"
print*, trim(iomsg)
end if
end subroutine temp_writer
end module temp_writer_module
Then you can use it in your program like this:
subroutine calc_temps(...)
use temp_writer_module
<variable declarations>
<calculations>
call temp_writer(tfield(100, 1:6))
end subroutine calc_temps
Just don't forget to call the temp_writer_close routine before your program ends.
I have a sub routine file as follows
subroutine grids(Ngrids,gridsize,boundx,boundy,boundz,occmatrix,myid)
implicit NONE
integer i,j,k,Ngrids, occmatrix(14,14,10)
integer locx,locy,locz,myid
double precision gridsize,boundx,boundy,boundz
do i = 1, 14
do j = 1, 14
do k = 1, 10
occmatrix(i,j,k) = 0
enddo
enddo
enddo
open (13, file = 'grid_data.9deg')
write(*,'(A,i2)'),' READING GRID FILE ON PROC.....',myid
read(13,*) Ngrids,gridsize
read(13,*) boundx,boundy,boundz
do i = 1, Ngrids
read(13,*) locx, locy, locz
occmatrix(locx,locy,locz) = 1
enddo
close(13)
return
end
It gives the following syntax error in compiling
subroutine grids(Ngrids,gridsize,boundx,boundy,boundz,occmatrix,my
1
Error: Unexpected junk in formal argument list at (1)
It used to run well before
I would believe, your line is to long. Did you add a new argument? Your code looks like free form, but it might be the compiler tried to apply fixed form due to a .f suffix in the filename or something like that. Convince the compiler to assume free formatted source code (by compiler options or usually a .f90 suffix).
Even in free formatted files your line width is limited and you should break longer lines, which would for example look like:
subroutine grids( Ngrids,gridsize,boundx,boundy,boundz, &
& occmatrix,myid )
If you are stuck with fixed format you need to indicate a continuation line by a non blank character in column 6.
Here is how it looks like in fixed form:
subroutine grids(Ngrids,gridsize,boundx,boundy,boundz,
& occmatrix,myid)
Please do not use fixed form anymore! Instead, change your files to end with .f90, most compilers recognize this for free formatted code.
I have some issues about opening and reading multiple files. I have to write a code which reads two columns in n files formatted in the same way (they are different only for the values...). Before this, I open another input file and an output file in which I will write my results. I read other questions in this forum (such as this one) and tried to do the same thing, but I receive these errors:
read(fileinp,'(I5)') i-49
1
devstan.f90:20.24:
fileLoop : do i = 50,52
2
Error: Variable 'i' at (1) cannot be redefined inside loop beginning at (2)
and
read(fileinp,'(I5)') i-49
1
Error: Invalid character in name at (1)
My files are numbered from 1 to n and are named 'lin*27-n.dat' (where n is the index starts from 1) and the code is:
program deviation
implicit none
character(len=15) :: filein,fileout,fileinp
integer :: row,i,h
real :: usv,usf,tsv,tsf,diff
write(*,'(2x,''Input file .......''/)')
read(*,'(a12)') filein
write(*,'(2x,''Output file........''/)')
read(*,'(a12)') fileout
open(unit = 30,File=filein)
open(unit = 20,File=fileout)
fileLoop : do i = 50,52
fileinp = 'lin*27-'
read(fileinp,'(I5)') i-49
open(unit = i,File=fileinp)
do row = 1,24
read(30,*) h,usv,tsv
read(i,*) h,usf,tsf
diff = usf - usv
write(20,*) diff
enddo
close(i)
enddo fileLoop
end program deviation
How can I solve it? I am not pro in Fortran, so please don't use difficult language, thanks.
The troublesome line is
read(fileinp,'(I5)') i-49
You surely mean to do a write (as in the example linked): this read statement attempts to read from the variable fileinp rather than writing to it.
That said, simply replacing with write is probably not what you need either. This will ignore the previous line
fileinp = 'lin*27-'
merely setting to, in turn, "1", "2", "3" (with leading blanks). Something like (assuming you intend that * to be there)
write(fileinp, '("lin*27-",I1)') i-49
Note also the use of I1 in the format, rather than I5: one may want to avoid blanks in the filename. [This is suitable when there is exactly one digit; look up Iw.m and I0 when generalizing.]
Is there a way to call the field of a derived type via string argument in fortran?
something like...
subroutine set(car, fieldName, value)
type(Car_T) :: car
character*(*) :: fieldName
character*(*) :: value
car%[fieldName] = value
end subroutine set
I know you can do stuff like this in javascript, c#, ect., but this could really help me from having a ton of duplicate code if fortran allows it.
No. You will need to write the executable code (perhaps a SELECT CASE construct) that maps the value of the string across to the relevant component.
You only need to write this once for each unique set of component names.
You can do something similar with namelists but it is for items known to the program: not new items.
integer:: inin
real:: rere
namelist /info/ inin, rere
inin = 0 ! default
rere = 20.4 ! default
read (*, nml=info)
print *, 'inin=', inin
print *, 'rere=', rere
stop
end
On the input
&info inin=2 rere=40.0 /
Or if you wish to input one value only
&info rere=3.162 /