C++中的引用常见用法

void &r=x; //不能建立void类型引用
int &&r=x; //不能建立引用的引用
int &*p=x; //不能建立指向引用的指针，但是可以建立指向指针的引用
int &ra[10]=a; //不能建立引用的数组

#include<iostream>
using namespace std;
int x=5,y=10;
int &r=x;
void print()
{
    cout<<"x="<<x<<" y=<<y<<" r="<<endl;
    cout<<"Address of x "<<&x<<endl;
    cout<<"Address of y "<<&y<<endl;
    cout<<"Address of z "<<&z<<endl;
}
int main()
{
    print();
    r=y;
     
    y=100;
    print();
    x=200;
    print();
    return 0;
}

运行结果如下：
x=5 y=10 r=5
Address of x 00474DD0
Address of y 00474DD4
Address of r 00474DD0
x=10 y=100 r=10
Address of x 00474DD0
Address of y 00474DD4
Address of r 00474DD0
x=200 y=100 r=200
Address of x 00474DD0
Address of y 00474DD4
Address of r 00474DD0

 1 #include <iostream>
 2 using namespace std;
 3 void swap(int &x,int &y)
 4 {
 5     int t=x;
 6     x=y;
 7     y=t;
 8 }
 9 int main()
10 {
11     int a=3,b=5,c=10,d=20;
12     cout<<"a="<<a<<" b="<<b<<endl;
13     swap(a,b);
14     cout<<"a="<<a<<" b="<<b<<endl;
15     cout<<"c="<<c<<" d="<<d<<endl;
16     swap(c,d);
17     cout<<"c="<<c<<" d="<<d<<endl;
18     return 0;
19 }