强制类型转化
```c++
cout<<(int)pow(2,a+1)-2;
```
by gxy001 @ 2019-11-15 16:01:25
$\texttt{cout << fixed << setprecision(0) << pow(2, a + 1) - 2 << endl;}$
by Lily_White @ 2019-11-15 16:02:49
```cpp
#include<iostream>
#include<math.h>
using namespace std;
int main()
{
int a;
cin>>a;
cout<<(int)pow(2,a+1)-2;
return 0;
}
```
by Li_Dicker @ 2019-11-15 16:03:42
@[gxy001](/user/55707) 谢谢，不过这里似乎要用高精
by microchip @ 2019-11-15 16:04:50
@[Ravenclaw_OIer](/user/87696) 变六十了，好像不对···
by microchip @ 2019-11-15 16:06:52
@[Ravenclaw_OIer](/user/87696) 谢谢，A了
by microchip @ 2019-11-15 16:20:52
@[microchip](/user/241838) 可以使用字符串流sscanf和sprintf操作
by 樱初音斗橡皮 @ 2019-11-15 16:25:56
@[樱初音斗橡皮](/user/66287) 怎么用，和printf scanf一样吗
by microchip @ 2019-11-15 16:27:29
@[microchip](/user/241838) printf/scanf是把当前要输出的内容打印到屏幕上，但sprintf/sscanf就相当于把当前要输出的内容打到字符串里。
by 樱初音斗橡皮 @ 2019-11-15 18:57:14