Namespace and Using

Question 1

What is a Namespace?

Answer 1

A place to store and provide scope to variables, functions, classes, etc. to provide obfuscation and avoid namespace collision.

Question 2

Namespace and Using

How do you create a namespace?

Answer 2

namespace namespace_name {
…Code in namespace…
}

Question 3

Namespace and Using

How do you reference a namespace?

Answer 3

• directly by name (namespace_name::var/function/class)
• via the ‘using’ keyword. (using namespace_name)

Question 4

Namespace and Using

If two files are imported with the same namespace, what happens?

Answer 4

The namespaces are merged into a single namespace.

Question 5

Namespace and Using

What is the default namespace?

Answer 5

The Global namespace

Question 6

Namespace and Using

What is the benefit of the global namespace?

Answer 6

Things in the global namespace can be accessed without ‘using’ or ‘::’

Question 7

What does the ‘using namsepace’ keyword do in a .cpp file?

Answer 7

It brings the mentioned namespace into the global namespace.

Question 8

What does the ‘using namsepace’ keyword do in a .h file?

Answer 8

It pulls the headerfile’s material in the mentioned space.

Question 9

Why should the ‘using’ keyword be avoided in .h files?

Answer 9

• It can create subnamespaces if namespaces are created in the .h file.
• It pulls the .h file into the “using” namespace rather than the global namespace.

Question 10

Namespace and Using

What is a subnamespace?

Answer 10

A namespace that can only be accessed from the namespace it was declared in.

Question 11

Namespace and Using

What does a directive allow you to do?

Answer 11

Specify single elements from a namespace that you can include in your global namespace.

Question 12

How do you declare a directive?

Answer 12

using namespace::element;

ex: using std::cout;

Question 13

What does the error “____ is ambiguous” signify?

Answer 13

That the namespace of an object / method needs to be specified as there is namespace collision.

Question 14

What is the ‘friend’ keyword?

Answer 14

It Grants access to viewing and interacting with the private member variables / methods of the class.

Question 15

What are the rules to the ‘friend’ keyword?

Answer 15

• Only offered, not taken.
• Not bidirectional.
• Friendship is not inherited.
• Inheritence is not friendship.

Question 16

What can you friend?

Answer 16

• Specific methods / functions
• entire classes

Question 17

What is the most common usage of friend?

Answer 17

The &laquo_space;output operator overload.

Question 18

Where is friendship declared?

Answer 18

Inside of the class that is granting access.

Question 19

What are the rules to friending a function?

Answer 19

• The function must be in the same namespace
• implementing them must be done in the same environment.

Question 20

Given Class MyClass and Struct MyStruct what is the syntax to friend each of these?

Answer 20

• friend class MyClass
• friend struct MyStruct

Question 21

Namespace and Using

Why would you use an alias longer than the command name?

Answer 21

If the type of certain variables needs to be updated, it allows you to update only 1 variable, rather than all of them.

Question 22

Namespace and Using

How do you create an Alias in C++?

Answer 22

using alias_name = command;

ex: using ll = long long;