void?main()?{
??var?list2?=?["h","e","l","l","o"];
??print(listTimes(list2,?times));?//打印?[hhh,?eee,?lll,?lll,?ooo]
??print(list2);??????????//打印?[hhh,?eee,?lll,?lll,?ooo]
??//print(list);?????????//報(bào)錯(cuò)不存在
}

List?listTimes?(List?list,?String?f(str))?{
??for?(var?index?=?0;?index?<?list.length;?++index)?{
????list[index]?=?f(list[index]);
??}
??return?list;
}
String?times(str)?{
??return?str*3;
}

把list2傳到listTimes里去，怎么list2也變成[hhh,?eee,?lll,?lll,?ooo]了，那要用到["h","e","l","l","o"]的時(shí)候怎么辦。怎么改進(jìn)