55 lines
917 B
C++
55 lines
917 B
C++
//
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// Created by light on 19-12-15.
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//
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#include <iostream> // std::cout/endl
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#include <utility> // std::move
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using namespace std;
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class Obj {
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public:
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Obj()
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{
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cout << "Obj()" << endl;
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}
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Obj(const Obj&)
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{
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cout << "Obj(const Obj&)"
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<< endl;
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}
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Obj(Obj&&)
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{
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cout << "Obj(Obj&&)" << endl;
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}
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};
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Obj simple()
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{
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Obj obj;
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// 简单返回对象；一般有 NRVO
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return obj;
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}
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Obj simple_with_move()
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{
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Obj obj;
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// move 会禁止 NRVO
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return std::move(obj);
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}
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Obj complicated(int n)
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{
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Obj obj1;
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Obj obj2;
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// 有分支，一般无 NRVO
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if (n % 2 == 0) {
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return obj1;
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} else {
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return obj2;
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}
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}
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int main()
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{
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cout << "*** 1 ***" << endl;
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auto obj1 = simple();
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cout << "*** 2 ***" << endl;
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auto obj2 = simple_with_move();
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cout << "*** 3 ***" << endl;
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auto obj3 = complicated(42);
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} |