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我们知道向vector容器里插入数据时使用insert函数，但是C++11又增加了一个emplace函数，它的功能与emplace_back原理一样，是构造一个对象添加到容器中，这样就省去了拷贝的副本，提高了性能，操作对比如下：

#include 
   
    #include 
    
     #include 
     
      using namespace std;typedef struct Personal{    int m_age;    int m_height;    string m_name;    Personal(int age, int height, std::string name)        :m_age(age), m_height(height), m_name(name)    {        //cout << "constructed=======Personal===age=" << age << endl;    }    Personal(const Personal& other)        :m_age(other.m_age)        , m_height(other.m_height)        , m_name(other.m_name)    {        //cout << "copy constructed====Personal==age=" << m_age << endl;    }    ~Personal()    {        //cout << "destructor~~~Personal=========age~" << m_age << endl;    }}Person;void insert_emplace_reserve_Test(){    int count = 214748;//214748    string name = string("床前明月光，疑似地上霜，举头望明月，低头思故乡。");    double startTime1 = clock();//1计算开始    vector
      
        vec1;    cout << "insert_emplace_reserve_Test==========" <
       
         vec3;    vec3.reserve(count);    double startTime3 = clock();//3计算开始    for(int i = 0; i < count; i++)    {        Person person(i, i, name);        vec3.emplace(vec3.begin() + i, person);    }    double endTime3 = clock();//3时间结束    cout << "vec3.size=" << vec3.size() << " vec3.capacity=" << vec3.capacity() << endl;    vec3.clear();    cout << "for    3 run time is: " << (double)(endTime3 - startTime3) / CLOCKS_PER_SEC << "s" << endl;    cout << endl;}int main(){    //int = [-2147483648, 2147483647]    insert_emplace_reserve_Test();    cout << endl;    cout << "Hello World!" << endl;    return 0;}
       
      
     
    
   

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