What is perfect forwarding in C++?

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**Perfect forwarding** — pass arguments to another function preserving their value category (lvalue/rvalue) and cv-qualifiers. ```cpp template void wrapper(T&& arg) { // Forward arg with its original value category target(std::forward(arg)); } void target(int& val) { std::cout << "lvalue "; } void target(int&& val) { std::cout << "rvalue "; } int x = 10; wrapper(x); // Calls target(int&) — lvalue wrapper(10); // Calls target(int&&) — rvalue wrapper(std::move(x)); // Calls target(int&&) — rvalue ``` **Why std::forward and not std::move:** - std::forward(arg) — preserves original value category. - std::move(arg) — always casts to rvalue. - Use std::forward in templates for forwarding. - Use std::move for explicit transfer of ownership.

C++: What is perfect forwarding in C++?