I use window 10. I use Xstart compiler.
The exact problem is to write type declarations to declare them as real variables.
Temperature, Pressure, Volume Type declarations are needed to declare these three as real variables.
I should print it and show the result.
Below is my program. To run the program I write pgf90 ww.f90.
Since a.out is the command that shows the latest calculation result, use a.out to print the result.
program disting
implicit none
REAL :: Temperature, Pressure, Volume print *
end program disting
When I run this program, I get this error.
error at or near identifier print (ww.f90: 3)
0 informs, 0 warnings, 1 severes, 0 fatal for disting.
Why is this not printing?
program disting
implicit none
REAL :: Temperature, Pressure, Volume
print *, Temperature, Pressure, Volume
end program disting
If you explicitly print out your variables it works fine. The * is not a wildcard, it simply tells the computer to output the data that follows in a format compatible with the type of items contained in the following comma delimited list. You were missing the list to print out.
I tested this here: https://www.jdoodle.com/execute-fortran-online/
Related
GCC version 4.6
The Problem: To find a way to feed in parameters to the executable, say a.out, from the command line - more specifically feed in an array of double precision numbers.
Attempt: Using the READ(*,*) command, which is older in the standard:
Program test.f -
PROGRAM MAIN
REAL(8) :: A,B
READ(*,*) A,B
PRINT*, A+B, COMMAND_ARGUMENT_COUNT()
END PROGRAM MAIN
The execution -
$ gfortran test.f
$ ./a.out 3.D0 1.D0
This did not work. On a bit of soul-searching, found that
$./a.out
3.d0,1.d0
4.0000000000000000 0
does work, but the second line is an input prompt, and the objective of getting this done in one-line is not achieved. Also the COMMAND_ARGUMENT_COUNT() shows that the numbers fed into the input prompt don't really count as 'command line arguments', unlike PERL.
If you want to get the arguments fed to your program on the command line, use the (since Fortran 2003) standard intrinsic subroutine GET_COMMAND_ARGUMENT. Something like this might work
PROGRAM MAIN
REAL(8) :: A,B
integer :: num_args, ix
character(len=12), dimension(:), allocatable :: args
num_args = command_argument_count()
allocate(args(num_args)) ! I've omitted checking the return status of the allocation
do ix = 1, num_args
call get_command_argument(ix,args(ix))
! now parse the argument as you wish
end do
PRINT*, A+B, COMMAND_ARGUMENT_COUNT()
END PROGRAM MAIN
Note:
The second argument to the subroutine get_command_argument is a character variable which you'll have to parse to turn into a real (or whatever). Note also that I've allowed only 12 characters in each element of the args array, you may want to fiddle around with that.
As you've already figured out read isn't used for reading command line arguments in Fortran programs.
Since you want to read an array of real numbers, you might be better off using the approach you've already figured out, that is reading them from the terminal after the program has started, it's up to you.
The easiest way is to use a library. There is FLAP or f90getopt available. Both are open source and licensed under free licenses.
The latter is written by Mark Gates and me, just one module and can be learned in minutes but contains all what is needed to parse GNU- and POSIX-like command-line options. The first is more sophisticated and can be used even in closed-source projects. Check them out.
Furthermore libraries at https://fortranwiki.org/fortran/show/Command-line+arguments
What READ (*,*) does is that it reads from the standard input. For example, the characters entered using the keyboard.
As the question shows COMMAND_ARGUMENT_COUNT() can be used to get the number of the command line arguments.
The accepted answer by High Performance Mark show how to retrieve the individual command line arguments separated by blanks as individual character strings using GET_COMMAND_ARGUMENT(). One can also get the whole command line using GET_COMMAND(). One then has to somehow parse that character-based information into the data in your program.
I very simple cases you just need the program requires, for example, two numbers, so you read one number from arg 1 and another form arg 2. That is simple. Or you can read a triplet of numbers from a single argument if they are comma-separated like 1,2,3 using a simple read(arg,*) nums(1:3).
For general complicated command line parsing one uses libraries such as those mentioned in the answer by Hani. You have set them up so that the library knows the expected syntax of the command line arguments and the data it should fill with the values.
There is a middle ground, that is still relatively simple, but one already have multiple arguments, that correspond to Fortran variables in the program, that may or may not be present. In that case one can use the namelist for the syntax and for the parsing.
Here is an example, the man point is the namelist /cmd/ name, point, flag:
implicit none
real :: point(3)
logical :: flag
character(256) :: name
character(1024) :: command_line
call read_command_line
call parse_command_line
print *, point
print *, "'",trim(name),"'"
print *, flag
contains
subroutine read_command_line
integer :: exenamelength
integer :: io, io2
command_line = ""
call get_command(command = command_line,status = io)
if (io==0) then
call get_command_argument(0,length = exenamelength,status = io2)
if (io2==0) then
command_line = "&cmd "//adjustl(trim(command_line(exenamelength+1:)))//" /"
else
command_line = "&cmd "//adjustl(trim(command_line))//" /"
end if
else
write(*,*) io,"Error getting command line."
end if
end subroutine
subroutine parse_command_line
character(256) :: msg
namelist /cmd/ name, point, flag
integer :: io
if (len_trim(command_line)>0) then
msg = ''
read(command_line,nml = cmd,iostat = io,iomsg = msg)
if (io/=0) then
error stop "Error parsing the command line or cmd.conf " // msg
end if
end if
end subroutine
end
Usage in bash:
> ./command flag=T name=\"data.txt\" point=1.0,2.0,3.0
1.00000000 2.00000000 3.00000000
'data.txt'
T
or
> ./command flag=T name='"data.txt"' point=1.0,2.0,3.0
1.00000000 2.00000000 3.00000000
'data.txt'
T
Escaping the quotes for the string is unfortunately necessary, because bash eats the first quotes.
GCC version 4.6
The Problem: To find a way to feed in parameters to the executable, say a.out, from the command line - more specifically feed in an array of double precision numbers.
Attempt: Using the READ(*,*) command, which is older in the standard:
Program test.f -
PROGRAM MAIN
REAL(8) :: A,B
READ(*,*) A,B
PRINT*, A+B, COMMAND_ARGUMENT_COUNT()
END PROGRAM MAIN
The execution -
$ gfortran test.f
$ ./a.out 3.D0 1.D0
This did not work. On a bit of soul-searching, found that
$./a.out
3.d0,1.d0
4.0000000000000000 0
does work, but the second line is an input prompt, and the objective of getting this done in one-line is not achieved. Also the COMMAND_ARGUMENT_COUNT() shows that the numbers fed into the input prompt don't really count as 'command line arguments', unlike PERL.
If you want to get the arguments fed to your program on the command line, use the (since Fortran 2003) standard intrinsic subroutine GET_COMMAND_ARGUMENT. Something like this might work
PROGRAM MAIN
REAL(8) :: A,B
integer :: num_args, ix
character(len=12), dimension(:), allocatable :: args
num_args = command_argument_count()
allocate(args(num_args)) ! I've omitted checking the return status of the allocation
do ix = 1, num_args
call get_command_argument(ix,args(ix))
! now parse the argument as you wish
end do
PRINT*, A+B, COMMAND_ARGUMENT_COUNT()
END PROGRAM MAIN
Note:
The second argument to the subroutine get_command_argument is a character variable which you'll have to parse to turn into a real (or whatever). Note also that I've allowed only 12 characters in each element of the args array, you may want to fiddle around with that.
As you've already figured out read isn't used for reading command line arguments in Fortran programs.
Since you want to read an array of real numbers, you might be better off using the approach you've already figured out, that is reading them from the terminal after the program has started, it's up to you.
The easiest way is to use a library. There is FLAP or f90getopt available. Both are open source and licensed under free licenses.
The latter is written by Mark Gates and me, just one module and can be learned in minutes but contains all what is needed to parse GNU- and POSIX-like command-line options. The first is more sophisticated and can be used even in closed-source projects. Check them out.
Furthermore libraries at https://fortranwiki.org/fortran/show/Command-line+arguments
What READ (*,*) does is that it reads from the standard input. For example, the characters entered using the keyboard.
As the question shows COMMAND_ARGUMENT_COUNT() can be used to get the number of the command line arguments.
The accepted answer by High Performance Mark show how to retrieve the individual command line arguments separated by blanks as individual character strings using GET_COMMAND_ARGUMENT(). One can also get the whole command line using GET_COMMAND(). One then has to somehow parse that character-based information into the data in your program.
I very simple cases you just need the program requires, for example, two numbers, so you read one number from arg 1 and another form arg 2. That is simple. Or you can read a triplet of numbers from a single argument if they are comma-separated like 1,2,3 using a simple read(arg,*) nums(1:3).
For general complicated command line parsing one uses libraries such as those mentioned in the answer by Hani. You have set them up so that the library knows the expected syntax of the command line arguments and the data it should fill with the values.
There is a middle ground, that is still relatively simple, but one already have multiple arguments, that correspond to Fortran variables in the program, that may or may not be present. In that case one can use the namelist for the syntax and for the parsing.
Here is an example, the man point is the namelist /cmd/ name, point, flag:
implicit none
real :: point(3)
logical :: flag
character(256) :: name
character(1024) :: command_line
call read_command_line
call parse_command_line
print *, point
print *, "'",trim(name),"'"
print *, flag
contains
subroutine read_command_line
integer :: exenamelength
integer :: io, io2
command_line = ""
call get_command(command = command_line,status = io)
if (io==0) then
call get_command_argument(0,length = exenamelength,status = io2)
if (io2==0) then
command_line = "&cmd "//adjustl(trim(command_line(exenamelength+1:)))//" /"
else
command_line = "&cmd "//adjustl(trim(command_line))//" /"
end if
else
write(*,*) io,"Error getting command line."
end if
end subroutine
subroutine parse_command_line
character(256) :: msg
namelist /cmd/ name, point, flag
integer :: io
if (len_trim(command_line)>0) then
msg = ''
read(command_line,nml = cmd,iostat = io,iomsg = msg)
if (io/=0) then
error stop "Error parsing the command line or cmd.conf " // msg
end if
end if
end subroutine
end
Usage in bash:
> ./command flag=T name=\"data.txt\" point=1.0,2.0,3.0
1.00000000 2.00000000 3.00000000
'data.txt'
T
or
> ./command flag=T name='"data.txt"' point=1.0,2.0,3.0
1.00000000 2.00000000 3.00000000
'data.txt'
T
Escaping the quotes for the string is unfortunately necessary, because bash eats the first quotes.
I am writing a subroutine and main function to call it, but getting error as undefined reference to ___. I found one reason: When I save the main and subroutine in the same file, compile and run that file, everything runs perfectly. However, when I save them into different .f90 files and try to run the main file, I get error. Is there any way I can make subroutine into a separate file and call into main calling program?
I got confused with another place - in the main program at !------ERROR------ place. I referred to Automatic width integer descriptor in fortran 90 I can use I0 as automatic width display indicator. But when I used the same, there is run time error expected integer but got character. Any idea about this?
! saved as sub_program.f90 file
SUBROUTINE sub_program (v1,v2,ctr)
IMPLICIT NONE
INTEGER, INTENT(IN) :: ctr
INTEGER, INTENT (OUT) :: v1,v2
SELECT CASE (ctr)
CASE (1)
v1=1
v2=0
CASE (2)
v1=0
v2=1
END SELECT
RETURN
END SUBROUTINE
! main calling program, saved as caller.f90
PROGRAM caller
IMPLICIT NONE
INTEGER :: v1,v2,ctr
DO ctr = 1,2,1
CALL sub_program (v1,v2,ctr)
WRITE (*,100) 'STEP = ',ctr,'V1 = ',v1,'V2 = ',v2 !------ERROR------
100 FORMAT (I0)
END DO
END PROGRAM
Thanks!
What is your compile command? For me, this compiles and runs normally
gfortran caller.f90 foo.f90 && ./a.out
I0 is an integer indicator, but some items following your WRITE statement are character strings. You can try, for example,
100 FORMAT (3(A, I0, 1X))
where 1X refers to a space.
As a note, if formatting is not terribly important and you're only interested in seeing some quick results, you can use the free format output (WRITE(*,*) ...).
EDIT: I had incorrectly referred to FORMAT as obsolete.
I've recently started working on an existing Fortran program, and picking up the language at the same time. I wrote the following subroutine:
subroutine timing(yyyy, mm, dd, var, ntime, time_blocks,
* time_day)
use myglobals
! ---------------------------------------------------------------------
! Common Variables
! ---------------------------------------------------------------------
integer yyyy, ! year
* mm, ! month
* dd, ! day
* ntime ! nr of blocks for which time was measured
real time_blocks(ntime),
* time_day
character*4 var
! ---------------------------------------------------------------------
! Internal Variables
! ---------------------------------------------------------------------
integer ios
integer out_unit=52
open(unit=out_unit, file=diroutput(1:69)//'timing',
* err=450, iostat=ios)
450 print*, "iostat= ", iostat
print*, "open"
write(out_unit, format_str) yyyy, mm, dd, var, time_blocks,
* time_day
return
end
The purpose of this subroutine is to write the inputs it gets from another part of the program to a file, following a defined format (format definition not included in my example). The file must be created on the first call of this subroutine, then accessed on each further call in order to append the new information. diroutput is a character string defined in myglobals.
My problem is that the program seems to get hung up at the OPEN statement, i.e. nothing happens until I kill the process. I ran the code with several print*, statements to locate the error, and found out this way that the error must be in the OPEN statement. It seems strange that the program does nothing at all, not even jump to the error label.
As I'm new to Fortran I might be missing something fairly obvious, so a quick look by someone more experienced might help. I'm certain that diroutput contains a valid path.
I'm using Linux (CentOS 5.5) and I compiled my program with Intel Fortran Compiler 11.1.
Your code seems, from the continuation characters in (generally) column 6, to be written in fixed-form despite containing features of Fortran 90. If it is fixed-form then statement labels, such as 450 should be in columns 1 to 5. I don't immediately see why that would cause the program to hang rather than crash, but I suggest you fix this and try again.
I am quite new in Fortran, and just got the program from a PhD. It is used to count the number of beads in certain histograms. Here is the code:
program xrdf
implicit none
include 'currentconf.fi'
real drdf,rdf12(200)
real xni12, Zface
integer ibead,iconf,ii,io,i,j,k,linecount
integer mchains, iendbead, nstart
logical ifend
Zface=1.5
mchains=49
drdf=0.1
xni12=0.
io=10
nstart=12636
open(file='pcushion.tr.xmol',unit=io)
do i=1,200
rdf12(i)=0.0
end do
ifend=.false.
do iconf=1,1000000
! reading current frame
ii=iconf
call readconf(io,ii,linecount,ifend)
write(*,*)' conf ',iconf,' N=',n
if (ifend) go to 777
! if trajectory ended, exit loop
ibead=0
do i=1,mchains
iendbead=nstart+i*45
dz=abs(Zface-z(iendbead))
ii=int(dz/drdf)+1
rdf12(ii)=rdf12(ii)+1
xni12=xni12+1.0
end do
end do !iconf
777 write(*,*)' total ',iconf-1,' frames '
write(*,*)' r rho(z) '
do i=1,200
write(*,'(f10.4,e15.7)')(i-0.5)*drdf,rdf12(i)/xni12
end do
close(io)
stop
end
Because I really do not know which part is wrong, so I just past all the code here. When I compile this program, there comes an error:
i=int(dz/drdf)+1
1
Error: Incompatible ranks 0 and 1 in assignment at (1)
How can I edit the program to fix it?
I was able to reproduce your compiler error using a simple program. It seems likely that in
ii=int(dz/drdf)+1
you are trying to assign an array (maybe dz?) to an integer (ii).
integer ibead,iconf,ii,io,i,j,k,linecount
Compare the dimensions of ii (dimension is 1) with the dimensions of dz and drdf.
This is my program (compiled it using gfortran):
PROGRAM TEST
implicit none
integer dz(10),ii
real dy
dz=3
dy=2.0
ii=int(dz/dy)+1
END PROGRAM TEST
Using ifort the error message is more revealing:
error #6366: The shapes of the array expressions do not conform