Copying a vector to a new instance

Understanding vector copying and memory semantics in C++

This is a medium-difficulty C++ language-knowledge question that tests your grasp of copy semantics and how standard library containers like std::vector behave when assigned or copied. It's the kind of question interviewers use to verify you understand the difference between shallow and deep copies, and when each occurs in the standard library.

To answer correctly, you need to trace through what happens when a vector is constructed from or assigned to another vector, paying close attention to whether the underlying data is shared or duplicated, and how that affects the observed output. Getting this right hinges on knowing the guarantees the C++ standard makes about container independence after a copy operation.

• Copy constructor vs. copy assignment operator
• Deep vs. shallow copying in containers
• Value semantics and object lifetime
• The relationship between copies and data ownership