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本文链接:https://blog.csdn.net/weixin_42528266/article/details/102753434
#include <iostream>
using namespace std;
class Person {
public:
static int ms_count;
};
class Student : public Person {
};
int Person::ms_count = 0;
int main() {
Person::ms_count = 20;
Student::ms_count = 10;
cout << Person::ms_count << endl;
getchar();
return 0;
}
//class Car {
//private:
// static int m_count;
//public:
// Car() {
// m_count++;
// }
// ~Car() {
// m_count--;
// }
// static int getCount() {
// return m_count;
// }
//};
//
//int Car::m_count = 0;
//
//int main() {
// /*Car car1;
// Car car2;
// Car *p = new Car();
// delete p;
//
// cout << car1.getCount() << endl;*/
//
// cout << Car::getCount() << endl;
//
// /*Car car1;
// car1.m_count = 10;
// car1.getCount();
//
// p->m_count = 10;
// p->getCount();
//
// Car::m_count = 20;
// Car::getCount();*/
//
// getchar();
// return 0;
//}
//class Car {
//public:
// static int m_price;
// void run() {
// cout << "run()" << endl;
//
// }
//};
//
//// 初始化静态成员变量
//int Car::m_price = 0;
//
//int main() {
// Car car;
// car.m_price = 10;
//
// Car car2;
// car2.m_price = 20;
//
// Car::m_price = 30;
//
// Car *p = new Car();
// p->m_price = 40;
//
// Car car3;
// cout << car3.m_price << endl;
//
//
// getchar();
// return 0;
//}
#include <iostream>
using namespace std;
/*
单例模式:
在程序运行过程中,可能会希望某些类的实例对象永远只有一个
1.把构造函数私有化
2.定义一个私有的静态成员变量指针,用于指向单例对象
3.提供一个公共的返回单例对象的静态成员函数
*/
//class Person {
//public:
// static int ms_count;
// virtual void run() {
//
// }
//};
//
//int Person::ms_count = 0;
//
//class Student : public Person {
//public:
// static int ms_count;
// void run() {
// ms_count = 10;
// }
//};
//
//int Student::ms_count = 0;
//
//
//int main() {
//
// Person::ms_count = 10;
// Student::ms_count = 20;
//
// cout << Person::ms_count << endl;
// cout << Student::ms_count << endl;
//
//
// getchar();
// return 0;
//}
class Rocket {
public:
// C++:静态成员函数
// Java、OC:类方法
static Rocket * sharedRocket() {
// API p_thread
if (ms_rocket == NULL) {
ms_rocket = new Rocket();
}
return ms_rocket;
}
static void deleteRocket() {
static Rocket *ms_rocket;
if (ms_rocket == NULL) return;
delete ms_rocket;
ms_rocket = NULL;
}
static Rocket *ms_rocket;
private:
Rocket() {
cout << "Rocket()" << endl;
}
~Rocket() {
cout << "~Rocket()" << endl;
}
};
Rocket *Rocket::ms_rocket = NULL;
int main() {
int *p = new int();
*p = 5;
delete p;
p = NULL;
cout << *p << endl;
// mac
// xcode
Rocket *p1 = Rocket::sharedRocket();
// ......
Rocket::deleteRocket();
Rocket *p2 = Rocket::sharedRocket();
Rocket::deleteRocket();
/*Rocket *p1 = Rocket::sharedRocket();
Rocket *p2 = Rocket::sharedRocket();
Rocket *p3 = Rocket::sharedRocket();
Rocket *p4 = p3->sharedRocket();
cout << p1 << endl;
cout << p2 << endl;
cout << p3 << endl;
cout << p4 << endl;*/
getchar();
return 0;
}
#include <iostream>
using namespace std;
class Car {
public:
int m_price;
// static const int msc_wheelsCount = 4;
Car() :m_price(0) {
}
static void test3() {
}
void test4() {
test1();
}
void test2() const {
// this->m_price = 20;
}
// 不能在这个函数内部修改当前对象的成员变量
void test1() const {
// this->m_price = 10;
test2();
test3();
}
void test() {
cout << "test()" << endl;
}
void test() const {
cout << "test() const" << endl;
}
};
int main() {
Car car;
car.test();
Car *p = new Car();
p->test();
const Car car2;
car2.test();
const Car *p2 = new Car();
p2->test();
/*Car car1;
car1.m_price = 100;
Car car2;
car2.m_price = 500;
cout << sizeof(Car) << endl;*/
getchar();
return 0;
}