tolower.f90

      SUBROUTINE tolower(string)
! convert a string to lower case
! note: string should NOT be a parameter (constant) or this seg faults
      CHARACTER (len=*) , INTENT(inout) :: string 
      INTEGER :: i,ic,nlen,icLow,icHigh,icDel
      
      iclow = ichar('A')
      ichigh = ichar('Z')
      icdel = ichar('a') - ichar('A')
      nlen = len(string) 
      DO i=1,nlen
         ic = ichar(string(i:i))
         IF (ic >= iclow .and. ic < ichigh) string(i:i) = char(ic+icdel)
      END DO 
 
      END SUBROUTINE tolower