Converting integer data to string in fortran 90

[s_hy]

hi all,

i have the following code:

do n = ninit,nlast  
character(len=20) :: filename
integer :: n
do n = 1,600
  write (filename, "I0") n
  open (unit=110,file='wave'//trim(filename)//'.dat',action = 'write',status = 'old')
  do i = iinit+1,ilast-1
   !boundary condition
     u(iinit,n+1) = 0
     u(ilast,n+1) = 0
     !end of boundary condition
     u(i,n+1) = 2*(1-(alpha**2))*u(i,n)-u(i,n-1) + (alpha**2)*(u(i+1,n)+u(i-1,n))

   Print*,'i,n,u(i,n+1)=',i,' ', n,' ', u(i,n+1)  
   Write (110,*)'i,n,u(i,n+1)=',i,' ', n,' ', u(i,n+1) 
   close  (unit = 110)
   end do !i
end do !n

what actually i want is to produce automatically a file at a time in the loop with the name ending in a counter, for example: wave1.dat, wave2.dat,wave3.dat,...,wave599.dat,wave600.dat...but, my programming didn't run properly. Can anyone advice what is wrong with my code.

thanks

 

[AlephZero]

If you say status='old', the file you want to open must already exist. Therefore your program problably won't work the first time your run it. (But it would work the second time, except that it didn't work the first time ... catch 22!)

You don't really need action='write' either, but it won't do any harm.

 

[gsal]

I personally would pad the numbers with zeroes on the left so that when you do a directory listing they actually show up in order :-)

program zzz
character(len=20) :: filename
integer :: n
do n = 1,100
  write (filename, "('wave',I3.3,'.dat')") n
  open (unit=110,file=filename,status = 'new')
  do i = iinit+1,ilast-1
   write (110,*)' whatever ' 
   close  (unit = 110)
   end do !i
  end do !n
end program zzz

this works.

 

[s_hy]

thank you gsal...it's work...

 

[LudusRex]

I would suggest that the issue with your code may be related to the use of the write statement. In Fortran 90, the write statement requires a format specifier, which is missing in your code. Without a format specifier, the write statement will not be able to convert the integer data to a string properly.

To fix this issue, you can use the "I0" format specifier in the write statement, which will convert the integer data to a string with the specified number of digits. For example, using "I3" will convert the integer 1 to the string "001".

In addition, I would recommend using the "newunit" keyword in the open statement instead of specifying the unit number manually. This will ensure that the unit number is not already in use and will prevent any potential conflicts.

I hope this helps and good luck with your programming!