详解C++ 左值引用与 const 关键字

//声明并初始化常规左值引用变量
int x = 55;
int & rx = x;
 
//将const关键字用于左值引用变量，以下几种为等效表示
int x = 55;
const int & crx = x;
int const & crx = x;

//初始化用法一：作为short变量别名
short x = 55;
short & rx = x;
cout << x;  //结果为55
cout << rx; //结果为55
cout << &x; //32位系统结果为0x0093F7BC
cout << &rx;//32位系统结果为0x0093F7BC
cout << sizeof(x); //结果为2
cout << sizeof(rx);//结果为2
 
//初始化用法二：作为short变量别名，多层引用
short x = 55;
short & rx = x;
short & rxx = rx;
 
//初始化用法三：作为short变量别名，指针表示法，指针为short*
short x = 55;
short * px = &x;
short & rx = *px;
 
//初始化用法四：作为short变量别名，指针表示法，指针为short *const
short x = 55;
short * const px = &x;
short & rx = *px;

//初始化用法一：作为short变量别名
short x = 55;
const short & rx = x;
 
//初始化用法二：作为const short变量别名
const short x = 55;
const short & rx = x;
 
//初始化用法三：作为short变量别名，多层引用
short x = 55;
short & rx = x;
const short & rxx = rx;
 
//初始化用法四：作为short变量别名，多层引用，第一层引用为const
short x = 55;
const short & rx = x;
const short & rxx = rx;
 
//初始化用法五：作为short变量别名，指针表示法，指针为short*
short x = 55;
short * px = &x;
const short & rx = *px;
 
//初始化用法六：作为short变量别名，指针表示法，指针为const short*
short x = 55;
const short * px = &x;
const short & rx = *px;
 
//初始化用法七：作为short变量别名，指针表示法，指针为short *const
short x = 55;
short *const px = &x;
const short & rx = *px;
 
//初始化用法八：作为short变量别名，指针表示法，指针为const short *const
short x = 55;
const short *const px = &x;
const short & rx = *px;
 
//初始化用法九：将创建临时变量，类型为int的非左值，字面常量
const int & rx = 100;
 
//初始化用法十：将创建临时变量，类型为int的非左值，多项表达式
const int & rx = 1+50*2;
 
//初始化用法十一：将创建临时变量，类型为int的非左值，函数返回int值
const int & rx = abs(10);
 
//初始化用法十二：将创建临时变量，类型不是int但可转换为int的变量
short x = 55;
const int & rx = x;
cout << x;  //结果为55
cout << rx; //结果为55
cout << &x; //32位系统结果为0x006FFCF0
cout << &rx;//32位系统结果为0x006FFCD8
cout << sizeof(x); //结果为2
cout << sizeof(rx);//结果为4
 
//初始化用法十三：将创建临时变量，类型不是int但可转换为int的非左值，字面常量
const int & rx = 100.0;
 
//初始化用法十四：将创建临时变量，类型不是int但可转换为int的非左值，多项表达式
const int & rx = 1.0+50.0*2.0;