Notes on features of CPP

While I am doing the CMU 15-445/645 :: Intro to Database Systems course, I need to learn C++.
I am using the cmu-db/15445-bootcamp repository to familiarise myself.

This is a very nice resource, but I do want to dig a little deeper into some concepts and I would write down the notes for those as a learn more.

Value Categories

Before learning the move semantics, we need to learn about the Value Categories. I don’t understand is well enough to explain it better. So I would suggest you watch the talk.

             expression
             /       \
          glvalue   rvalue
          /     \  /     \
      lvalue   xvalue    prvalue

My vague understanding is :

• lvalue : refers to something that is stored in memory, often appers on the left side of the expresstion. x in this expression int x = 10 is lvalue.
• rvalue : anything that is not lvalue, 10 is ravlue in int x = 10.
• xvalue : refers to expiring lvalue, basically something which is stored on memory, but the program doesn’t have a way to refer to the memory location yet, so the reference will be garbage collected after the scope is destroyed.

References

• Back to Basics: Understanding Value Categories - Ben Saks - CppCon 2019 - YouTube

Move semantics

x

Reference