main.cpp

#include <Teacher.h>
#include <iostream>

using namespace std;

void fun() {
	MyTeacher teacher;

	teacher.setAge(18);
	teacher.setName("小明");

	cout << "teacher name : " << teacher.getName() << endl;
	cout << "teacher age : " << teacher.getAge() << endl;
}
//值傳遞
void setFunc(MyTeacher teacher) {
	teacher.setAge(16);
	teacher.setName("jhone");
	cout << "teacher name : " << teacher.getName() << endl;
	cout << "teacher age : " << teacher.getAge() << endl;
}
//引用傳遞
void setFuncY(MyTeacher &teacher) {
	teacher.setAge(16);
	teacher.setName("jhone");
	cout << "teacher name : " << teacher.getName() << endl;
	cout << "teacher age : " << teacher.getAge() << endl;
}

void main() {
	
 
//fun();


	//MyTeacher teacher;
	//teacher.setAge(20);
	//teacher.setName("小明");


	MyTeacher teacher = MyTeacher("xiaohong", 25);//沒new關鍵字的是物件


	MyTeacher *teacher1 = new MyTeacher("xiaohong", 25);//有new關鍵字是指標 不會走虛構函式 需要自己釋放


	delete teacher1;//釋放物件 才會走虛構函式
	teacher1 = nullptr;


	cout << "teacher name : " << teacher.getName() << endl;
	
 
cout << "teacher age : " << teacher.getAge() << endl;
	setFuncY(teacher);
	cout << "teacher name : " << teacher.getName() << endl;
	cout << "teacher age : " << teacher.getAge() << endl;
	system("pause");
}

#pragma once
class MyTeacher
{
public:
	MyTeacher();//建構函式 (malloc)
	~MyTeacher();//虛構函式 釋放在建構函式裡面動態申請的記憶體 (free)

	void setAge(int age);
	int getAge();

	void setName(char *name);
	char* getName();
private:
	int age;
	char *name;
};
 

#include <Teacher.h>
#include<iostream>


using namespace std;

//建立名稱空間
namespace NSP_A {
	struct MyStudent
	{
		int age;
	};
}

MyTeacher::MyTeacher()
{
	std::cout << "MyTeacher 建構函式 " << this << std::endl;
}

MyTeacher::~MyTeacher()
{
	//使用了std的名稱空間 就可以不要前面的std限定符
	cout << "MyTeacher 虛構函式 " << this << std::endl;
}

void MyTeacher::setAge(int age) {
	this->age = age;

	//名稱空間的使用
	NSP_A::MyStudent t;
	t.age = 18;

	using NSP_A::MyStudent;
	MyStudent t2;
	t2.age = 16;
}
int MyTeacher::getAge() {
	return this->age;
}

void MyTeacher::setName(char *name) {
	this->name = name;
}
char* MyTeacher::getName(){
	return this->name;
}

淺拷貝和深拷貝

MyStudent.h

class MyStudent
{
public:
	MyStudent(int age,char*name,char *teacherName);
	~MyStudent();
	//重寫預設的拷貝建構函式
	MyStudent(const MyStudent &student);

public:
	int age;
	char *name;
	char *teacherName;

private:

};

#include <MyStudent.h>
#include <iostream>

using namespace std;

MyStudent::MyStudent(int age, char*name, char *teacherName):age(age),name(name),teacherName(teacherName)
{
	cout << "無參建構函式" << this << endl;
}

MyStudent::~MyStudent()
{
	cout << "虛構函式" << this << endl;
}

//預設拷貝建構函式 淺拷貝
MyStudent::MyStudent(const MyStudent &student) {
	cout << "拷貝建構函式" << this << endl;
	this->age = student.age;
	this->name = student.name;
	this->teacherName = student.teacherName;
}

main.cpp

void copyTest() {
	MyStudent student = MyStudent(21, "jake", "jhone");
	MyStudent stu2 = student;//也會呼叫拷貝建構函式
}9:58 2017/10/23

void main() {
	copyTest();
	system("pause");
}

注意：淺拷貝可能引出的問題 我在建構函式申請一塊記憶體， 虛構函式去釋放這塊記憶體 當我退出時釋放記憶體 由於拷貝的物件是執行的拷貝建構函式 這裡沒有申請記憶體 用的是同一塊記憶體 這塊記憶體釋放後 執行拷貝物件虛構函式時 會丟擲異常 是由野指標造成的 

問題產生

#include <MyStudent.h>
#include <iostream>

using namespace std;

MyStudent::MyStudent(int age, char*name, char *teacherName):age(age)
{
	cout << "無參建構函式" << this << endl;

	int len = strlen(name);
	this->name = (char *)malloc(len + 1);
	strcpy(this->name, name);

	len = strlen(teacherName);
	this->teacherName = (char *)malloc(len + 1);
	strcpy(this->teacherName, teacherName);
}

MyStudent::~MyStudent()
{
	cout << "虛構函式" << this << endl;
	free(this->name);
	free(this->teacherName);

}

//預設拷貝建構函式 淺拷貝
MyStudent::MyStudent(const MyStudent &student) {
	cout << "拷貝建構函式" << this << endl;
	this->age = student.age;
	this->name = student.name;
	this->teacherName = student.teacherName;
}

解決淺拷貝可能存在的問題 在拷貝函式重新申請空間 就可以了

MyStudent::MyStudent(const MyStudent &student) {
	cout << "拷貝建構函式" << this << endl;
	this->age = student.age;
	//this->name = student.name;
	int len = strlen(student.name);
	this->name = (char *)malloc(len + 1);
	strcpy(this->name, student.name);
	//this->teacherName = student.teacherName;
	len = strlen(student.teacherName);
	this->name = (char *)malloc(len + 1);
	strcpy(this->name, student.teacherName);
}