program volatile_doctest use stringifor_string_t type(string) :: astring type(string) :: yetanotherstring character(len=:), allocatable :: acharacter logical :: test_passed(1) astring = 'Hello ' acharacter = 'World!' yetanotherstring = acharacter.cat.astring test_passed(1) = yetanotherstring%chars()=='World!Hello ' print '(L1)', all(test_passed) endprogram volatile_doctest