Consider the following code:

```
#include <iostream>

using namespace std;

int main () {

srand(time(0));
double dd [10];
for(int i=0;i!=10; ++i) dd[i]= rand()%5+0;

for(auto i:dd)
cout<<i<<' ';

cout<<endl;

exit(100);

}

```

Why is it compiling without the `#include<ctime>` and `#include<cstdlib>` for the calls to `time(0)` and `exit(100)`(which is absolutely useless there, I know)? Are they already included in `iostream`?