C++ 2017 Work [ 2025-2027 ]

Compile-time conditional compilation inside templates, discarding non-taken branches entirely.

// in a header inline int global_counter = 0; Mandates copy elision for prvalues, making certain moves/constructors unnecessary even conceptually. c++ 2017

std::optional<int> parse_int(const std::string& s) try return std::stoi(s); catch(...) return std::nullopt; Compile-time conditional compilation inside templates

std::vector<int> v(1'000'000); std::for_each(std::execution::par, v.begin(), v.end(), [](int& x) x *= 2; ); Portable filesystem operations: paths, directories, permissions, etc. Mandates copy elision for prvalues

Allows declaring a variable scoped to the statement.

if (auto it = m.find(key); it != m.end()) // use it here // it goes out of scope Permits defining variables in header files without violating the One Definition Rule (ODR). Essential for header-only libraries.

std::map<int, std::string> src1,"a"; std::map<int, std::string> dst; dst.insert(src.extract(1)); Distinct enum class for raw memory representation (no arithmetic).