class Person
{
  public:
  //構(gòu)造函數(shù)
  Person()
 {
  cout << "Person的構(gòu)造函數(shù)調(diào)用" << endl;
 }
//析構(gòu)函數(shù)
~Person()
 {
   cout << "Person的析構(gòu)函數(shù)調(diào)用" << endl;
 }
};
void test01()
{
  Person p;
}
int main()
 {
   test01();
   system("pause");
   return 0;
 }

//1、構(gòu)造函數(shù)分類
// 按照參數(shù)分類分為 有參和無(wú)參構(gòu)造 無(wú)參又稱為默認(rèn)構(gòu)造函數(shù)
// 按照類型分類分為 普通構(gòu)造和拷貝構(gòu)造
class Person {
public:
 
//無(wú)參（默認(rèn)）構(gòu)造函數(shù)
Person() {
cout << "無(wú)參構(gòu)造函數(shù)!" << endl;
}
 
//有參構(gòu)造函數(shù)
Person(int a) {
age = a;
cout << "有參構(gòu)造函數(shù)!" << endl;
}
 
//拷貝構(gòu)造函數(shù)
Person(const Person& p) {
age = p.age;
cout << "拷貝構(gòu)造函數(shù)!" << endl;
}
 
//析構(gòu)函數(shù)
~Person() {
cout << "析構(gòu)函數(shù)!" << endl;
}
 
public:
int age;
};
 
//2、構(gòu)造函數(shù)的調(diào)用
//調(diào)用無(wú)參構(gòu)造函數(shù)
void test01() {
Person p; //調(diào)用無(wú)參構(gòu)造函數(shù)
}
 
//調(diào)用有參的構(gòu)造函數(shù)
void test02() {
//2.1 括號(hào)法，常用
Person p1(10);
//注意1：調(diào)用無(wú)參構(gòu)造函數(shù)不能加括號(hào)，如果加了編譯器認(rèn)為這是一個(gè)函數(shù)聲明
//Person p2();
 
//2.2 顯式法
Person p2 = Person(10);
Person p3 = Person(p2);
//Person(10)單獨(dú)寫就是匿名對(duì)象 當(dāng)前行結(jié)束之后，馬上析構(gòu)
 
//2.3 隱式轉(zhuǎn)換法
Person p4 = 10; // Person p4 = Person(10);
Person p5 = p4; // Person p5 = Person(p4);
//注意2：不能利用 拷貝構(gòu)造函數(shù) 初始化匿名對(duì)象 編譯器認(rèn)為是對(duì)象聲明
//Person p5(p4);
}
int main() {
test01();
//test02();
system("pause");
return 0;
}

class Person {
public:
Person() {
cout << "無(wú)參構(gòu)造函數(shù)!" << endl;
mAge = 0;
}
Person(int age) {
cout << "有參構(gòu)造函數(shù)!" << endl;
mAge = age;
}
Person(const Person& p) {
cout << "拷貝構(gòu)造函數(shù)!" << endl;
mAge = p.mAge;
}
//析構(gòu)函數(shù)在釋放內(nèi)存之前調(diào)用
~Person() {
cout << "析構(gòu)函數(shù)!" << endl;
}
public:
int mAge;
};
//1. 使用一個(gè)已經(jīng)創(chuàng)建完畢的對(duì)象來(lái)初始化一個(gè)新對(duì)象
void test01() {
Person man(100); //p對(duì)象已經(jīng)創(chuàng)建完畢
Person newman(man); //調(diào)用拷貝構(gòu)造函數(shù)
Person newman2 = man; //拷貝構(gòu)造
//Person newman3;
//newman3 = man; //不是調(diào)用拷貝構(gòu)造函數(shù)，賦值操作
}
//2. 值傳遞的方式給函數(shù)參數(shù)傳值
//相當(dāng)于Person p1 = p;
void doWork(Person p1) {}
void test02() {
Person p; //無(wú)參構(gòu)造函數(shù)
doWork(p);
}
//3. 以值方式返回局部對(duì)象
Person doWork2()
{
Person p1;
cout << (int *)&p1 << endl;
return p1;
}
void test03()
{
Person p = doWork2();
cout << (int *)&p << endl;
}
int main() {
//test01();
//test02();
test03();
system("pause");
return 0;
}

class Person {
public:
//無(wú)參（默認(rèn)）構(gòu)造函數(shù)
Person() {
cout << "無(wú)參構(gòu)造函數(shù)!" << endl;
}
//有參構(gòu)造函數(shù)
Person(int a) {
age = a;
cout << "有參構(gòu)造函數(shù)!" << endl;
}
//拷貝構(gòu)造函數(shù)
Person(const Person& p) {
age = p.age;
cout << "拷貝構(gòu)造函數(shù)!" << endl;
}
//析構(gòu)函數(shù)
~Person() {
cout << "析構(gòu)函數(shù)!" << endl;
}
public:
int age;
};
void test01()
{
Person p1(18);
//如果不寫拷貝構(gòu)造，編譯器會(huì)自動(dòng)添加拷貝構(gòu)造，并且做淺拷貝操作
Person p2(p1);
cout << "p2的年齡為： " << p2.age << endl;
}
void test02()
{
//如果用戶提供有參構(gòu)造，編譯器不會(huì)提供默認(rèn)構(gòu)造，會(huì)提供拷貝構(gòu)造
Person p1; //此時(shí)如果用戶自己沒(méi)有提供默認(rèn)構(gòu)造，會(huì)出錯(cuò)
Person p2(10); //用戶提供的有參
Person p3(p2); //此時(shí)如果用戶沒(méi)有提供拷貝構(gòu)造，編譯器會(huì)提供
//如果用戶提供拷貝構(gòu)造，編譯器不會(huì)提供其他構(gòu)造函數(shù)
Person p4; //此時(shí)如果用戶自己沒(méi)有提供默認(rèn)構(gòu)造，會(huì)出錯(cuò)
Person p5(10); //此時(shí)如果用戶自己沒(méi)有提供有參，會(huì)出錯(cuò)
Person p6(p5); //用戶自己提供拷貝構(gòu)造
}
int main() {
test01();
system("pause");
return 0;
}

class Person {
public:
//無(wú)參（默認(rèn)）構(gòu)造函數(shù)
Person() {
cout << "無(wú)參構(gòu)造函數(shù)!" << endl;
}
//有參構(gòu)造函數(shù)
Person(int age ,int height) {
cout << "有參構(gòu)造函數(shù)!" << endl;
m_age = age;
m_height = new int(height);
cout << "拷貝構(gòu)造函數(shù)!" << endl;
//如果不利用深拷貝在堆區(qū)創(chuàng)建新內(nèi)存，會(huì)導(dǎo)致淺拷貝帶來(lái)的重復(fù)釋放堆區(qū)問(wèn)題
m_age = p.m_age;
m_height = new int(*p.m_height)
}
//拷貝構(gòu)造函數(shù)
Person(const Person& p) {
;
}
//析構(gòu)函數(shù)
~Person() {
cout << "析構(gòu)函數(shù)!" << endl;
if (m_height != NULL)
{
delete m_height;
}
}
public:
int m_age;
int* m_height;
};
void test01()
{
Person p1(18, 180);
Person p2(p1);
cout << "p1的年齡： " << p1.m_age << " 身高： " << *p1.m_height << endl;
cout << "p2的年齡： " << p2.m_age << " 身高： " << *p2.m_height << endl;
}
int main() {
test01();
system("pause");
return 0;
}