program volatile_doctest use stringifor_string_t type(string) :: astring logical :: test_passed(2) astring = 'abcdefghilmnopqrstuvz' test_passed(1) = (astring%reverse()//''=='zvutsrqponmlihgfedcba') astring = '0123456789' test_passed(2) = (astring%reverse()//''=='9876543210') print '(L1)', all(test_passed) endprogram volatile_doctest