modern-cpp-tutorial/code/3/3.6.move.semantics.cpp

//
// 3.5.move.semantics.cpp
// modern c++ tutorial
//
// created by changkun at changkun.de
// https://github.com/changkun/modern-cpp-tutorial
//

#include <iostream> // std::cout
#include <utility>  // std::move
#include <vector>   // std::vector
#include <string>   // std::string

int main() {
    
    std::string str = "Hello world.";
    std::vector<std::string> v;
    
    // use push_back(const T&), copy
    v.push_back(str);
    // "str: Hello world."
    std::cout << "str: " << str << std::endl;
    
    // use push_back(const T&&), no copy
    // the string will be moved to vector, and therefore std::move can reduce copy cost
    v.push_back(std::move(str));
    // str is empty now
    std::cout << "str: " << str << std::endl;
    
    return 0;
}