### Pointer Basic
```cpp
#include
using namespace std;
int main()
{
int a = 10;
int *p;
int **pp;
int ***ppp;
p = &a;
pp = &p;
ppp = &pp;
cout << *p << endl; // 10
cout << **pp << endl; // 10
cout << ***ppp << endl;// 10
*p = 20;
cout << a << endl; // 20
cout << **pp << endl; // 20
cout << ***ppp << endl;// 20
return 0;
}
```