C++对象参数传递的三种方式是什么？值传递指针传递引用传递详解

#include <iostream>
using namespace std;

class Square //正方形
{
public:
    Square(double len) :length(len) //构造函数
    {}
    void set(double len) //修改边长
    {
        length = len;
    }
    double get()//获取边长的值
    {
        return length;
    }
    void show(); //输出面积
private:
	double length;//边长
};

void Square::show() //输出面积
{
    cout << "正方形面积:" << length * length << endl;
}

void Add(Square s)//只是修改形参的值,对实参没有影响
{
    double len = s.get() + 1; //len=原边长+1;
    s.set(len);//修改s的边长
}
int main()
{
    Square s(2);
    cout << "边长增加前:" << endl;
    s.show();
    Add(s);
    cout << "边长增加后:" << endl;
    s.show();
    return 0;
}

class Square //正方形
{
public:
    Square(double len) :length(len) //构造函数
    {}
    void set(double len) //修改边长
    {
        length = len;
    }
    double get()//获取边长的值
    {
        return length;
    }
    void show(); //输出面积
private:
	double length;//边长
};

void Square::show() //输出面积
{
    cout << "正方形面积:" << length * length << endl;
}

void Add(Square *ps)//传递的是指针,形参可以修改实参的值
{
    double len = ps->get() + 1; //len=原边长+1;
    ps->set(len);//修改ps指向的边长
}
int main()
{
    Square s(2);
    cout << "边长增加前:" << endl;
    s.show();
    Add(&s);
    cout << "边长增加后:" << endl;
    s.show();
    return 0;
}

class Square //正方形
{
public:
    Square(double len) :length(len) //构造函数
    {}
    void set(double len) //修改边长
    {
        length = len;
    }
    double get()//获取边长的值
    {
        return length;
    }
    void show(); //输出面积
private:
	double length;//边长
};

void Square::show() //输出面积
{
    cout << "正方形面积:" << length * length << endl;
}

void Add(Square &s)//形参是引用,可以改变实参的值
{
    double len = s.get() + 1; //len=原边长+1;
    s.set(len);//修改ps指向的边长
}
int main()
{
    Square squ(2);
    cout << "边长增加前:" << endl;
    squ.show();
    Add(squ);
    cout << "边长增加后:" << endl;
    squ.show();
    return 0;
}

//值传递
void increase1(int n)
{
    cout << "值传递," << &n << endl;
    n++;//修改形参的值
}
//引用传递
void increase(int& n)
{
    cout << "引用传递," << &n <<endl;
    n++;
}
//指针传递
void increase(int* n)
{
    cout << "指针传递," << &*n<<endl;
    *n = *n + 1;
}
int main()
{
    int n = 10;
    cout << "&n=" << &n<<",n="<<n<<endl;
    increase1(n);
    cout <<  "值传递,新n=" << n<<endl;
    increase(n);
    cout <<  "引用传递,新n=" << n<<endl;
    increase(&n);
    cout <<  "指针传递,新n=" << n << endl;
    return 0;
}