伪代码:open_source_file
open_new_filefor i = 1 to line_number_to_read
    read_in_one_line_from_source_file
    write_to_new_file
nextwrite_new_line_to_new_filedo while(there_is_more_lines_in_source_file)
   read_in_one_line_from_source_file
   write_to_new_file
enddoclose_source_file
close_new_file' now new_file is what you want