Advanced C++ Topics

Nested Classes and Name Spaces

Instead of using a prefix qualifier, if there are no conflicts we can just start a program with a using declaration.
This allows us to use cout instead of std::cout.
Since you create name spaces to avoid name clashes, you want to name them in a unambiguous (usually long) way, such as ACME_Software_San_Jose_CA_US.
Unfortunately, it would be painful to constantly type
```
ACME_Software_San_Jose_CA_US::map
```
You can define a short alias for a long name space.
```
namespace acme = ACME_Software_San_Jose_CA_US
```