int main()
{
	int a;
	int &b = a;
}

#include <iostream>
using namespace std;
int main()
{
	int a,b;
	int &r = a;
	int &r = b; //錯(cuò)誤，不可更改原有的引用關(guān)系
	float &rr = b; //錯(cuò)誤，引用類型不匹配
	cout<<&a<<&r<<endl; //變量與引用具有相同的地址。
	int &ra = r; //可對(duì)引用更次引用，表示 a 變量有兩個(gè)別名，分別是 r 和 ra
}

void swap(int a, int b); //無法實(shí)現(xiàn)兩數(shù)據(jù)的交換
void swap(int *p, int *q); //開辟了兩個(gè)指針空間實(shí)現(xiàn)交換

#include <iostream>
using namespace std;
void swap(int &a, int &b){
	int tmp;
	tmp = a;
	a = b;
	b = tmp;
}
int main(){
	int a = 3,b = 5;
	cout<<"a = "<<a<<"b = "<<b<<endl;
	swap(a,b);
	cout<<"a = "<<a<<"b = "<<b<<endl;
	return 0;
}

int a;
int* p = &a;
int*& rp = p; // ok
int& r = a;
int&& rr = r;//error

#include <iostream>
using namespace std;
void swap(char *pa,char *pb)
{
	char *t;
	t=pa;
	pa=pb;
	pb=t;
}
void swap2(char **pa,char **pb)
{
	char *t;
	t=*pa;
	*pa=*pb;
	*pb=t;
}
void swap3(char *&pa,char *&pb)//指針的引用
{
	char *t;
	t=pa;
	pa=pb;
	pb=t;
}
int main()
{
	char *pa="china";
	char *pb="america";
	cout<<"pa"<<pa<<endl;
	cout<<"pb"<<pb<<endl;
	//swap(pa,pb);
	//swap2(&pa,&pb);
	swap3(pa,pb);
	cout<<"pa"<<pa<<endl;
	cout<<"pb"<<pb<<endl;
	return 0;
}

int a;
int* p = &a;
int** pp = &p; // ok
int& r = a;
int&* pr = &r; // error

int a, b, c;
int* parr[] = {&a, &b, &c}; // ok
int& rarr[] = {a, b, c}; // error
int arr[] = {1, 2, 3};
int (&rarr)[3] = arr; // ok

double val = 3.14;
const int &ref = val; // int const & int & const ??
double & ref2 = val;
cout<<ref<<" "<<ref2<<endl;
val = 4.14;
cout<<ref<<" "<<ref2<<endl;

int temp = val;
const int &ref = temp;

int i=5;
const int & ref = i+5;
//此時(shí)產(chǎn)生了與表達(dá)式等值的無名的臨時(shí)變量，
//此時(shí)的引用是對(duì)無名的臨時(shí)變量的引用。故不能更改。
cout<<ref<<endl;

struct TypeP
{
	char *p;
};
struct TypeC
{
	char c;
};
struct TypeR
{
	char& r; //把引用單列出來，不與具體的對(duì)象發(fā)生關(guān)系
};
int main()
{
	printf("%d %d %d\n",sizeof(TypeP),sizeof(TypeC),sizeof(TypeR));
	return 0;
}

1、const int *pi                                   指向常量的指針。
2、int * const pi                                  指針本身是一個(gè)常量，稱為“指針常量”、“常指針”。
3、const int * const pi                       指向常量的指針常量。