C++引用的详细解释

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

#include <iostream>
using namespace std;
int main()
{
	int a,b;
	int &r = a;
	int &r = b; //错误，不可更改原有的引用关系
	float &rr = b; //错误，引用类型不匹配
	cout<<&a<<&r<<endl; //变量与引用具有相同的地址。
	int &ra = r; //可对引用更次引用，表示 a 变量有两个别名，分别是 r 和 ra
}

void swap(int a, int b); //无法实现两数据的交换
void swap(int *p, int *q); //开辟了两个指针空间实现交换

#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)//指针的引用
{
	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;
//此时产生了与表达式等值的无名的临时变量，
//此时的引用是对无名的临时变量的引用。故不能更改。
cout<<ref<<endl;

struct TypeP
{
	char *p;
};
struct TypeC
{
	char c;
};
struct TypeR
{
	char& r; //把引用单列出来，不与具体的对象发生关系
};
int main()
{
	printf("%d %d %d\n",sizeof(TypeP),sizeof(TypeC),sizeof(TypeR));
	return 0;
}

1、const int *pi                                   指向常量的指针。
2、int * const pi                                  指针本身是一个常量，称为“指针常量”、“常指针”。
3、const int * const pi                       指向常量的指针常量。