STL 之 utility pair swap move

一时失言乱红尘 2021-06-24 15:57 284阅读 0赞

**pair：**

// make_pair example
    #include <utility> // std::pair
    #include <iostream> // std::cout
    
    int main () {
      std::pair <int,int> foo;
      std::pair <int,int> bar;
    
      foo = std::make_pair (10,20);
      bar = std::make_pair (10.5,'A'); // ok: implicit conversion from pair<double,char>
    
      std::cout << "foo: " << foo.first << ", " << foo.second << '\n';
      std::cout << "bar: " << bar.first << ", " << bar.second << '\n';
    
      return 0;
    }

**swap：**

// swap algorithm example (C++11)
    #include <iostream> // std::cout
    #include <utility> // std::swap
    
    int main () {
    
      int x=10, y=20;                  // x:10 y:20
      std::swap(x,y);                  // x:20 y:10
    
      int foo[4];                      // foo: ? ? ? ?
      int bar[] = {
       10,20,30,40};       // foo: ? ? ? ? bar: 10 20 30 40
      std::swap(foo,bar);              // foo: 10 20 30 40 bar: ? ? ? ?
    
      std::cout << "foo contains:";
      for (int i: foo) std::cout << ' ' << i;
      std::cout << '\n';
    
      return 0;
    }
    结果：foo contains: 10 20 30 40

**move:**

// move example
    #include <utility> // std::move
    #include <iostream> // std::cout
    #include <vector> // std::vector
    #include <string> // std::string
    
    int main () {
      std::string foo = "foo-string";
      std::string bar = "bar-string";
      std::vector<std::string> myvector;
    
      myvector.push_back (foo);                    // copies
      myvector.push_back (std::move(bar));         // moves
    
      std::cout << "myvector contains:";
      for (std::string& x:myvector) std::cout << ' ' << x;
      std::cout << '\n';
    
      return 0;
    }
    结果：myvector contains: foo-string bar-string