//Reserving vector to avoid copy of object when we push_back above capacity // Normal push_back on class object vector: copy constructor is called // emplace_back on class object vector : copy constructor is not called...saved operations and memory allocation de-allocation //If not to go for emplace_back, still you can avoid copy constructor call by using reference_wrapper #include #include #include #include //for reference_wrapper using namespace std; class Person { char* m_name; public: Person(char* name) { int intLen=0; while(name[intLen]!='\0') { intLen++; } m_name = new char[intLen+1]; strcpy(m_name,name); cout << "Welcome " << m_name << endl; } Person(const Person& obj) { int intLen=0; while(obj.m_name[intLen]!='\0') { intLen++; } m_name = new char[intLen+1]; strcpy(m_name,obj.m_name); cout << "Welcome " << m_name << endl; } ~Person() { cout << "Bye bye " << m_name << endl; delete[] m_name; } void setName(char* name) { strcpy(m_name,name); } }; int main() { { Person objP1((char*)"Ketan"); Person objP3(objP1); objP1.setName((char*)"Ketan_1"); Person objP2((char*)"Ketan_2"); } cout < vecPerson; vecPerson.reserve(10); Person objP1((char*)"A"); vecPerson.push_back(objP1); Person objP2((char*)"B"); vecPerson.push_back(objP2); } cout < vecPerson; vecPerson.reserve(10); vecPerson.emplace_back((char*)"A"); vecPerson.emplace_back((char*)"B"); } cout < vecPerson; //Above is directly not allowed...So, we are using reference_wrapper vector> vecPerson; vecPerson.reserve(10); Person objP1((char*)"A"); vecPerson.push_back(objP1); Person objP2((char*)"B"); vecPerson.push_back(objP2); //if you have Person temp = vecPerson[0];then new copy is created Person& temp = vecPerson[0]; temp.setName((char*)"A_1"); //without getting reference object, we can do with get member function. //Note that vecPerson[1].setName((char*)"B_1"); will not compile vecPerson[1].get().setName((char*)"B_1"); } return 0; }