c++ 2.0 总结

khlbat / 2023-06-19 / 原文

class 内存分配与释放

#include <iostream>
#include <memory>

using namespace std;

class Person {
public:
    Person() {
        cout << "person constructor" << endl;
    }

    ~Person()
    {
        cout << "person destructor" << endl;
    }

    void sayHello()
    {
        cout << "person say hello" << endl;
    }
};



static void f1()
{
    cout << "不用指针:" << endl;
    auto p = Person();
}

static void f2() {
    cout << "new/delete:" << endl;
    auto p = new Person();
    delete p;
}

static void f3() {
    cout << "unique_ptr:" << endl;
    auto p = make_unique<Person>();
}

static void f5(const shared_ptr<Person> & p) {
    p->sayHello();
}

static void f4()
{
    cout << "shared_ptr 传参:" << endl;
    auto p = make_shared<Person>();
    f5(p);
    p->sayHello();
}

static void f6(const unique_ptr<Person>& p) {
    p->sayHello();
}

static void f5() {
    cout << "unique_ptr 传参:" << endl;
    auto p = make_unique<Person>();
    f6(p);
    p->sayHello();
}


int main()
{
    
    f1();
    cout << "================================" << std::endl;
    
    f2();
    cout << "================================" << std::endl;

    f3();
    cout << "================================" << std::endl;

    f4();
    cout << "================================" << std::endl;

    cout << "shared_ptr" << endl;
    f5();
    return 0;
}

输出

不用指针:
person constructor
person destructor
================================
new/delete:
person constructor
person destructor
================================
unique_ptr:
person constructor
person destructor
================================
shared_ptr 传参:
person constructor
person say hello
person say hello
person destructor
================================
shared_ptr
unique_ptr 传参:
person constructor
person say hello
person say hello
person destructor