How to name output files, making it related to a variable (in fortran)?

Question

Eg. The integer variable (m) will take the following values one by one:

1, 2, 3, ....

For each value of m, an array

p(i) (i=1,2,..., 1000)

is obtained and written in a output file with

open() and write()

Could you tell me how to name these output files as

file1.dat, file2.dat, file3.dat, …

Thanks.

Write the integer into an array and adjustl that string, the concatanate it with the pre- and post-fix? — haraldkl, Mar 27 '14 at 17:27
@haraldkl I do not need to write the integer into arrays ,but just want to name the output files, making these files include specific value of m, therefore they are distinguishable. — jiadong, Mar 27 '14 at 17:45
See http://stackoverflow.com/questions/1262695/converting-integers-to-strings-in-fortran and http://stackoverflow.com/questions/16291270/looping-over-variable-file-names — M. S. B., Mar 27 '14 at 21:42

haraldkl · Accepted Answer · 2014-03-28T14:09:16.813

3

So, here is a suggestion:

integer :: m
integer :: fu
character(len=10) :: file_id
character(len=50) :: file_name

! Write the integer into a string:
write(file_id, '(i0)') m

! Construct the filename:
file_name = 'file' // trim(adjustl(file_id)) // '.dat'

! Open the file with this name
open(file = trim(file_name), unit = fu)

Note, that you could also obtain leading zeroes with the iX.Y format string.

edited Mar 28 '14 at 14:09

answered Mar 27 '14 at 21:33

haraldkl

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Thanks for your very helpful answer and comments. In the last line, I replace `name` with `file`. I tried and then it works! – jiadong Mar 28 '14 at 10:00
Oh, sorry. Corrected that now. – haraldkl Mar 28 '14 at 14:09

Fortranner · Answer 2 · 2014-03-27T20:07:24.550

1

Googling "internal write fortran" shows how to create strings that embed the integer variable, which is demonstrated in the following program, which creates the string "file1.dat".

program internal_write
character (len=10) :: file_name
write (file_name,"('file',i0,'.dat')") 1
print*,"file name is ",trim(file_name)
end program internal_write

edited Mar 27 '14 at 20:07

answered Mar 27 '14 at 19:44

Fortranner

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How to name output files, making it related to a variable (in fortran)?

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