Differences in the use of function call pointer parameters *p, * & P

The following procedure , The comparison shows that when the function call pointer , Parameter is *p、*&p The difference between

#include<iostream>
#include<stdio.h>
using namespace std;

void change2(int *x){
    
	cout<<"change2: x->"<<x<<endl;//x Namely p Shape parameter ,x The value is a The address of  
	cout<<"change2: &x->"<<&x<<endl;//&x Namely x The address of  
	cout<<"change2:*&x->"<<*&x<<endl;//*&x Namely x The value pointed to by the address of , That is to say a The address of  
	++x;
}

void change1(int *&x){
    
	cout<<"change1: x->"<<x<<endl;//x Namely p Actual parameters ,x The value is a The address of . It can be understood as *(&x), What's coming in is p In itself  
	cout<<"change1: &x->"<<&x<<endl;//&x Namely x The address of  
	cout<<"change1:*&x->"<<*&x<<endl;//*&x Namely x The value pointed to by the address of , That is to say a The address of  
	++x;
}

int main(){
    
	int a = 10,b = 20;
	int *p1 = &a,*p2 = &b;
// cout<<*p<<endl;
	cout<<"&a:"<<&a<<",p1:"<<p1<<endl;
	change1(p1);
	cout<<"p1 after change1:"<<p1<<endl;
	cout<<endl<<endl;
// p = a; 
	cout<<"&b:"<<&b<<",p2:"<<p2<<endl;
	change2(p2);
	cout<<"p2 after change2:"<<p2<<endl;
// cout<<*p<<endl;
	return 0;
} 

We can see , It's also a pointer , The form of the passed in parameter is *p、*&p In the function of and after self addition , The result is different .

This explanation , If you don't write &, The pointer passed in is the formal parameter , Analogy to main Functional a、b Two variables are passed in void swap(int a,int b) The function is the same , about main Function a、b There will be no exchange ;

And wrote & Function of , It's like main Functional a、b Two variables are passed in void swap(int &a,int &b) In exchange for main function a、b Two variable values , Incoming in the form of address is a、b The actual address of , Will naturally main Functional a、b The values of the two variables are exchanged .

in short ：x The value of is a The address of ,&x yes x The address of , and *&x It is x The value of the address of , That is to say a The address of （ The address of the address ）.

If the address character is not passed &, Pointer parameter ; If the address character is passed &, Is a pointer argument .