Fortran Issue

[coil87]

Hi everyone!
I have a problem in compiling a program i made in fortran because of an error that occur in this line:
str=char(iachar('0')+ord/10)char(iachar('0')+mod(ord,10))'.par'
open(lin,file=str,status='old')
I have defined ord as an integer, and str as a character, and that particular portion of code is insered in a do cicle (do ord=1,10) because i want that the program open the file named 01.par 02.par ... 09.par 10.par

How can i fix it?
Thank you for your answers

 

[mikrom]

For converting number to string use write and for concatenation of strings use //

Example:

[COLOR=#a020f0]program[/color] num_str
  [COLOR=#2e8b57][b]integer[/b][/color] :: nr
  [COLOR=#2e8b57][b]character[/b][/color][COLOR=#804040][b]*[/b][/color][COLOR=#ff00ff]2[/color] :: nr_char
  [COLOR=#2e8b57][b]character[/b][/color][COLOR=#804040][b]*[/b][/color][COLOR=#ff00ff]12[/color] :: fname

  [COLOR=#804040][b]do[/b][/color] nr [COLOR=#804040][b]=[/b][/color] [COLOR=#ff00ff]1[/color], [COLOR=#ff00ff]10[/color]
    [COLOR=#804040][b]write[/b][/color](nr_char,[COLOR=#ff00ff]'(i2.2)'[/color]) nr
    fname [COLOR=#804040][b]=[/b][/color] [COLOR=#ff00ff]'file_'[/color][COLOR=#804040][b]//[/b][/color]nr_char[COLOR=#804040][b]//[/b][/color][COLOR=#ff00ff]'.par'[/color]
    [COLOR=#804040][b]write[/b][/color]([COLOR=#804040][b]*[/b][/color],[COLOR=#804040][b]*[/b][/color]) fname
  [COLOR=#804040][b]end do[/b][/color]
[COLOR=#a020f0]end program[/color] num_str

Output:

$ gfortran num_str.f95 -o num_str

$ num_str
 file_01.par 
 file_02.par 
 file_03.par 
 file_04.par 
 file_05.par 
 file_06.par 
 file_07.par 
 file_08.par 
 file_09.par 
 file_10.par

 

[FJacq]

str=char(iachar('0')+ord/10)char(iachar('0')+mod(ord,10))'.par'

This instruction is wrong. You need to merge string using the operator // :

str=char(iachar('0')+ord/10)//char(iachar('0')+mod(ord,10))//'.par'

But as mentioned by mikrom, another technique is possible : the internal write. For instance :

write(str,"(I0,A)") ord,'.par'

Notice that the format I0 (instead of I2.2 as proposed by mikrom) is more general and valid for any integer number.



François Jacq

 

[mikrom]

But using this format descriptor

write(nr_char,[highlight]'(I2.2)'[/highlight]) nr

you will get leading zeros in filenames

file_[highlight]01[/highlight].par
...

Using this format descriptor

write(nr_char,[highlight]'(I0)'[/highlight]) nr

suppresses leading zeros, so you will get

file_[highlight]1[/highlight] .par 
...

 

[coil87]

Thank you so much for your answers! I appreciate your collaboration!

If i want to insert the line

str=char(iachar('0')+ord/10)//char(iachar('0')+mod(ord,10))//'.par'

or

write(nr_char,'(I2.2)') nr

in a Subroutine such as

program main
 do ord=1,10
call read
end do
end main
subroutine read
 write(nr_char,'(I2.2)') ord
 fname = 'file_'//nr_char//'.par'
 open(1,file=fname,status'old')

How can i fix this problem?
That's the real case i'm interested in to.
Thank you for your patience, i've recently started programming in fortran

 

[mikrom]

You have to get ord or fname as an argument of the subroutine, i.e

subroutine read(ord)
  integer, intent(in) :: ord
  ...
end subroutine read

or

subroutine read(fname)
  character(*), intent(in) :: fname
  ...
end subroutine read