[here](https://www.luogu.com.cn/ide)
by Smile_Cindy @ 2020-08-06 19:52:49
UB,全是UB
by Arkadyevna @ 2020-08-06 19:54:21
@[Alpha](/user/87058)
本机的freopen结果是对的,但是在IDE上是零
by 想要个红名 @ 2020-08-06 19:56:32
@[Arkadyevna](/user/363937)
UB是什么嗷
by 想要个红名 @ 2020-08-06 19:56:54
我觉得你快读这样写就有问题……
by littleKtian @ 2020-08-06 20:08:49
@[想要个红名](/user/261414) UB指未定义行为
For example:
```cpp
int a=0;
a=a++;
```
今年有一篇日报里面有介绍的,可以翻一翻
by myee @ 2020-08-06 20:09:34
为啥getchar一次就直接while啊
by littleKtian @ 2020-08-06 20:10:03
是不是因为windows环境下的换行符和linux环境下不一样所以你getchar就读错了?
by 传奇666666 @ 2020-08-06 20:10:40
@[想要个红名](/user/261414) 不是如果你数前面有空格没读你这数就读不了
by Spasmodic @ 2020-08-06 20:17:46
谢谢所有大佬,我那个快读太老古了,是在之前本校OJ上用的,现在改了。
谢谢各位大佬的爆切(逃
by 想要个红名 @ 2020-08-06 20:21:58