program volatile_doctest use stringifor_string_t type(string) :: astring logical :: test_passed(2) astring = '^\s \d+\s*' test_passed(1) = astring%escape(to_escape='\')//''=='^\\s \\d+\\s*' test_passed(2) = astring%escape(to_escape='\', esc='|')//''=='^|\s |\d+|\s*' print '(L1)', all(test_passed) endprogram volatile_doctest