Fortran Trim() problem

[xrayspex1]

hi all, can anyone maybe explain to me what i am doing wrong with the TRIM function, because it doesn't actually remove any blanks from my string. The code is here:

program trim_err
implicit none
character(30) :: my_string
my_string = ' 123465 '
print *, '|'//my_string//'|'
my_string = trim(my_string)
print *, '|'//my_string//'|'
end program trim_err

This produces the following output (of length 30):
| 123465 |
| 123465 |

Any ideas would be appreciated!

 

[gullipe]

Hi xrayspex1

In F77 I usually use LEN_TRIM to remove trailing spaces.
Note the use of "my_string(1:len)", but not "my_string" in the write statement.

     program trim_err
     implicit none
       character*30 my_string
       integer*2 len
       my_string = ' 123465  '
       len = len_trim(my_string)
       write(*,'(1x,a)') '|'//my_string(1:len)//'|'
     end

 

[xwb]

program trim_err
   implicit none
   character(30) :: my_string    
   my_string = ' 123465  '    
   print *, '|'//my_string//'|'
   
   ! Since mystring is 30 characters long, you will still get 30 characters
   my_string = trim(my_string)    
   print *, '|'//my_string//'|'
   ! This will remove the traling spaces.  
   print *, '|'//trim(my_string)//'|'
   ! Another way of removing trailing spaces
   print *, '|'//my_string(1:len_trim(my_string))//'|'
   stop
end program trim_err

 

[xwb]

If you need to use the trimmed string a lot, then it is better to pass it to another subroutine. For instance, if your code looks like

open (10, trim(my_string) // '1.dat', status='old')
open (20, trim(my_string) // '2.dat', status='old')
open (30, trim(my_string) // '3.dat', status='old')
open (40, trim(my_string) // '4.dat', status='old')
...

It would be better if you did

call openfiles(trim(my_string))
...
subroutine openfiles (prefix)
character*(*) prefix
open (10, prefix // '1.dat', status='old')
open (20, prefix // '2.dat', status='old')
open (30, prefix // '3.dat', status='old')
open (40, prefix // '4.dat', status='old')
...

prefix would be the trimmed string of the correct length.