Subroutine LENCH for program GSAS2CIF

This subroutine is used to find the length of an ASCII string. Trailing spaces, tab & null characters are ignored. See the gsas2cif documentation for an explanation of this code. 

link to documentation
      INTEGER*4 FUNCTION LENCH(STR)
C---------------------------------------------------------------------------
c      Function LENCH
c
c This function takes a character string and finds out how long the
c "actual" string is (i.e. not including padded blanks on the right).
c
C---------------------------------------------------------------------------
!Calling arguments:

      CHARACTER*(*) STR                 

!Local variables:

      CHARACTER*1   NUL,TAB             
      LOGICAL*4     DONE                

!Data:

      data      nul      /0/
      data      tab      /'      '/

!Code:

      if ( str.ne.' ' .and. str(1:1).ne.nul ) then
        ilench = len(str)+1
        done = .false.
        do while ( .not.done .and. ilench.gt.0 )
          ilench = ilench-1
          if ( str(ilench:ilench).ne.' '
     1      .and. str(ilench:ilench).ne.tab            !Look for trailing tabs as well
     1      .and. str(ilench:ilench).ne.nul ) done=.true.
        END DO
        lench = ilench
      else
        lench=0
      end if
      return
      end