sairate
4108f6c42d
- 新增现代 C++ 教程的 Preface 章节，包括英文和中文版本 - 添加 C++ Primer 练习代码 - 新增 Learn C++ 教程的 C++ 开发简介章节 - 添加头文件解析文档 - 更新 mkdocs.yml，包含新教程的目录结构 - 修改项目设置，使用 Python 3.10环境
39 lines
1.2 KiB
C++
39 lines
1.2 KiB
C++
//
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// 3.3.rvalue.cpp
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// modern c++ tutorial
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//
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// created by changkun at changkun.de
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// https://github.com/changkun/modern-cpp-tutorial
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//
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#include <iostream>
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#include <string>
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void reference(std::string& str) {
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std::cout << "lvalue" << std::endl;
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}
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void reference(std::string&& str) {
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std::cout << "rvalue" << std::endl;
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}
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int main()
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{
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std::string lv1 = "string,"; // lv1 is a lvalue
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// std::string&& r1 = lv1; // illegal, rvalue can't ref to lvalue
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std::string&& rv1 = std::move(lv1); // legal, std::move can convert lvalue to rvalue
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std::cout << rv1 << std::endl; // string,
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const std::string& lv2 = lv1 + lv1; // legal, const lvalue reference can extend temp variable's lifecycle
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// lv2 += "Test"; // illegal, const ref can't be modified
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std::cout << lv2 << std::endl; // string,string
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std::string&& rv2 = lv1 + lv2; // legal, rvalue ref extend lifecycle
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rv2 += "string"; // legal, non-const reference can be modified
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std::cout << rv2 << std::endl; // string,string,string,
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reference(rv2); // output: lvalue
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return 0;
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}
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