STL中list和vector在添加元素时push_back会调用拷贝构造函数

 #include <iostream>

 #include <list>

 #include <vector>

 #include <cstring>

 using namespace std;

 class B

 {

 public:

     B()

     {

         cout<<"B()"<<endl;

     }

     void print()

     {

         cout<<"print"<<endl;

         p = NULL;

         len = ;

     }

     B(const B& b)

     {

         cout<<"copy B()"<<endl;

         if(p)

         {

             delete b.p;

             len = len;

             p = new char[len];

             memcpy(p, b.p, len);

         }

     }

     ~B()

     {

         cout<<"~B()"<<endl;

         if(p)

         {

             delete []p;

             p = NULL;

             len = ;

         }

     }

     char *p;

     int len;

 };

 int main()

 {

     list<B> ls;

     vector<B> vec;

     B b;

     ls.push_back(b);

     vec.push_back(b);

     return ;

 }

执行结果：