Does volatile variable have allocated memory?

Question

```cpp
volatile int var = 10;
std::cout << &var;//prints 1
```
I think it doesn't allocated memory. But why it print 1?

Answer 1

It does allocate memory.
Normally when iostream prints the address of a variable it converts it to a void* and then calls the operator<< overload that prints void*.
However no such overload exists for volatile void* and iostream's next best option is to convert it to a bool, which explains why it prints a 1. The same thing happens to function pointers.

If you want to print the address of a volatile variable you can either cast it to void* yourself:
std::cout << (void*)&var;

or overload the operator<< volatile void* for iostream.
std::ostream& operator<<( std::ostream& os, const volatile void* p )
{
return os << (void*)p;
}
...
std::cout << &var;