更新std :: map中的值? [英] Update a value in std::map?
问题描述
如果我有:
std :: map< int,intm;
我在哪里:
m.insert(std :: make_pair(1,2));
如何将值更新为7与key = 1相关联?
我在想:
(* m.find(1))。second = 7;
但是没有更简单的方法吗?
If I have:
std::map<int,intm;
where I have:
m.insert(std::make_pair(1,2));
how do I update the value to 7 associated with key = 1?
I was thinking:
(*m.find(1)).second = 7;
But is there no simpler way?
推荐答案
在4íj,13:37,桌面< f ... @ sss.comwrote:
On 4 íj, 13:37, desktop <f...@sss.comwrote:
如果我有:
std :: map< int,intm;
我在哪里:
m.insert(std :: make_pair(1,2));
如何更新与key = 1相关的值为7?
我在想:
(* m.find(1))。second = 7 ;
但是没有更简单的方法吗?
If I have:
std::map<int,intm;
where I have:
m.insert(std::make_pair(1,2));
how do I update the value to 7 associated with key = 1?
I was thinking:
(*m.find(1)).second = 7;
But is there no simpler way?
m [1] = 7;
m[1] = 7;
On4íj,13:38,Ondra Holub< ondra.ho ... @ post.czwrote:
On 4 íj, 13:38, Ondra Holub <ondra.ho...@post.czwrote:
在4íj,13:37,桌面< f ... @ sss.comwrote:
On 4 íj, 13:37, desktop <f...@sss.comwrote:
如果我有:
If I have:
std :: map< int,intm;
std::map<int,intm;
我在哪里:
where I have:
m.insert(std: :make_pair(1,2));
m.insert(std::make_pair(1,2));
如何将值更新为7与key = 1相关联?
how do I update the value to 7 associated with key = 1?
我在想:
I was thinking:
(* m.find( 1))。second = 7;
(*m.find(1)).second = 7;
但是没有更简单的方法吗?
But is there no simpler way?
m [1] = 7;
m[1] = 7;
请注意,operator []有副作用。如果地图中没有该关键值
,则添加新的关键值。但是对于你的使用它应该是
ok。
Please note, operator[] has "side effect". In case, that key value is
not present in map, new one is added. But for your usage it should be
ok.
10月4日晚上9:37,桌面< f。 .. @ sss.comwrote:
On Oct 4, 9:37 pm, desktop <f...@sss.comwrote:
如果我有:
std :: map< int,intm;
我在哪里:
m.insert(std :: make_pair(1,2));
如何将值更新为7与key = 1相关联?
我在想:
(* m.find (1))。second = 7;
但是没有更简单的方法吗?
If I have:
std::map<int,intm;
where I have:
m.insert(std::make_pair(1,2));
how do I update the value to 7 associated with key = 1?
I was thinking:
(*m.find(1)).second = 7;
But is there no simpler way?
是:
m [1] = 7;
但是检查在你这样做之前你有一个价值为
的钥匙,因为如果确实没有,那么它将会被创造出来。
使用map :: find会员查看。
-
Chris Val
Yes:
m[1]=7;
But check that you have a key with a value
of 1 before doing that, because if it does
not exist, it will be created.
Use the map::find member to check it.
--
Chris Val
>
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