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// 3.3.rvalue.cpp

// modern c++ tutorial

// created by changkun at changkun.de

// https://github.com/changkun/modern-cpp-tutorial

#include <iostream>

#include <string>

void reference(std::string& str) {

std::cout << "lvalue" << std::endl;

}

void reference(std::string&& str) {

std::cout << "rvalue" << std::endl;

}

int main()

{

std::string lv1 = "string,"; // lv1 is a lvalue

// std::string&& r1 = lv1; // illegal, rvalue can't ref to lvalue

std::string&& rv1 = std::move(lv1); // legal, std::move can convert lvalue to rvalue

std::cout << rv1 << std::endl; // string,

const std::string& lv2 = lv1 + lv1; // legal, const lvalue reference can extend temp variable's lifecycle

// lv2 += "Test"; // illegal, const ref can't be modified

std::cout << lv2 << std::endl; // string,string

std::string&& rv2 = lv1 + lv2; // legal, rvalue ref extend lifecycle

rv2 += "string"; // legal, non-const reference can be modified

std::cout << rv2 << std::endl; // string,string,string,

reference(rv2); // output: lvalue

return 0;

}