What-value

Understanding C++ value categories in code classification

This intermediate C++ question tests your fluency with the formal value-category system that underpins modern C++ semantics. Rather than computation or algorithm design, it demands precise knowledge of how the language categorizes expressions—a skill essential for writing correct template code, understanding move semantics, and debugging subtle type-deduction issues.

The question asks you to classify each statement in a given code snippet according to the C++11 taxonomy: lvalue (persistent object with an address), rvalue (temporary that will be destroyed), xvalue (expiring value—an rvalue reference to an object with identity), and prvalue (pure rvalue—a temporary with no persistent identity). Mastery of these distinctions is critical for understanding overload resolution, move constructors, perfect forwarding, and when temporaries are materialized.

• Rvalue references and move semantics
• Function overload resolution and reference binding rules
• Temporary materialization and object lifetime
• std::move and std::forward in generic code