pattern_query Function

    integer function pattern_query(lstring,lpattern)
    !---------------------------------------------------------------------------
    ! Searches a string for a PATTERN of characters. Returns zero if the pattern 
    ! is not found, or if the pattern or string is empty.
    !---------------------------------------------------------------------------

    ! arguments
    character(len=*), intent(in) :: lstring
    character(len=*), intent(in) :: lpattern

    ! local variables
    integer :: k, klast, ncount
    integer :: len_string, len_pattern

    ! initialize variables
    ncount = 0
    klast = 0
    len_string = len(lstring)
    len_pattern = len( trim(adjustL(lpattern)) )
    
    !---------------------------------------------------------------------------
    ! error check - conduct the search only if the pattern & string are not empty
    !---------------------------------------------------------------------------
    if( (len_pattern > 0) .and. (len_string > 0) ) then
       !------------------------------------------------------------------------
       ! examine the string to find the find the FIRST instance of the pattern 
       !------------------------------------------------------------------------
       k = index(lstring(klast+1:len_string), trim(adjustL(lpattern) ))
       do while( k > 0 )
          !---------------------------------------------------------------------
          ! if index is nonzero, there is at least one match, increment
          ! through the string checking for additional matches. 
          !---------------------------------------------------------------------
          ncount = ncount + 1    ! count match
          klast = k + klast      ! slide forward in string looking for next match
          k = index(lstring(klast+1:len_string), trim(adjustL(lpattern) ))
       enddo     ! while
    endif 
    
    pattern_query = ncount
    !---------------------------------------------------------------------------
    end function pattern_query