C++ Advanced Topics: 10 Questions

Here are the 10 questions to test your C++ advanced topics skills (correct answers are marked in BOLD):

You want to use std::map as a lookup table, but you might have several entries with the same key. You should use:

• std::multimap
• std::map, this isn’t a problem
• std::map with vector instances for the values
• std::duplimap

Which of these is not an advantage of std::string over char* strings?

• move semantics are implemented for you
• memory is automatically cleaned up
• there are less opportunities to code off-by-one-bugs
• strings take up less memory on the free store

When is it a good design to use a raw pointer as a member variable?

• When you are willing to write code to manage the lifetime
• When the compiler will generate lifetime management code for you
• When the pointer is only used to call methods, not for lifetime
• Never

In the statement x = update(b+c,d); which of these is an rvalue?

• x
• b+c
• b+c,d
• d

Some files that include a header to get a definition of a class can instead just use a forward reference. Which of these kinds of code can do that?

• Code that only calls public methods of the class
• Code that accesses methods of the class only through a pointer
• Code that doesn’t call methods or declare instances of the class
• Code that is in a friend class of the class

When should you choose list over vector?

• Never
• When you’ve measured a performance difference in your own application
• When you will insert and delete more often than you will traverse
• When the objects in the container are large

Which of these statements about standard algorithms is true

• They may be slower than code you write yourself
• They may be faster than code you write yourself
• They cannot be faster than code you write yourself
• They are always faster than code you write yourself

The standard vector will use move semantics if possible. Which contained elements can’t be moved unless you write a move constructor and move assignment operator?

• objects with standard vector instances as member variables
• objects with standard unique_pr instances as member variables
• objects with a destructor
• standard string instances

When is the best time to mark a member function as const?

• never
• after it’s tested and working
• before anyone else writes code that calls it
• before you write it

If a lambda captures a local by reference, what bad thing may happen?

• The lambda itself cannot be put into a variable
• The lambda will not be able to change the captured value
• The value may go out of scope before the lambda uses it
• The lambda cannot call a function

–EOF (The Ultimate Computing & Technology Blog) —