Several examples of pointer transfer, parameter transfer, value transfer, etc

  Code ：

#include<iostream>
using namespace std;
// The first function uses pointers in the form of value passing , All the changes are limited to the inside of the function ,
// When the function is executed, the value of the pointer itself will not be changed , It doesn't change what the pointer is pointing to .
void SwapPoint1(int *p,int *q){
	int * tmp = p;
	p = q;
	q = tmp;
}
// The second function also uses pointers in the form of value passing ,
// But inside the function, the memory is accessed directly by dereference and the content indicated by the pointer is modified .
void SwapPoint2(int *p,int *q){
	int  tmp = *p;
	*p = *q;
	*q = tmp;
}
// The parameter form of the function is int *&,
// Its meaning is , This parameter is a reference , The referenced object is a... In memory int  The pointer ,
// In this way, you can treat the pointer as an object , Exchange the value of the pointer itself . It should be noted that ,
// Now that the last function exchanges pointers , Of course, the result of dereferencing the pointer will change accordingly .
void SwapPoint3(int *&p,int *&q){
	int * tmp = p;
	p = q;
	q = tmp;
}


int main(){
	int a=5,b=10;
	int *p = &a, *q = &b;
	cout<<" Exchange before p The value of is ："<< p<<"\t"<<"q The value of is ："<<q<<endl;
 	cout<<" Exchange before p The value is ："<<*p<<"\t"<<"q The value is ："<<*q<<endl;
	cout<<endl;
	SwapPoint1(p,q); 
 	cout<<" After exchanging p The value of is ："<< p<<"\t"<<"q The value of is ："<<q<<endl;
 	cout<<" After exchanging p The value is ："<<*p<<"\t"<<"q The value is ："<<*q<<endl;
 	
 	cout<<endl; 
	a = 5,b = 10;
 	p = &a,q = &b; 
  	cout<<" Exchange before p The value of is ："<< p<<"\t"<<"q The value of is ："<<q<<endl;
 	cout<<" Exchange before p The value is ："<<*p<<"\t"<<"q The value is ："<<*q<<endl;
 	cout<<endl;
 	SwapPoint2(p,q); 
 	cout<<" After exchanging p The value of is ："<< p<<"\t"<<"q The value of is ："<<q<<endl;
 	cout<<" After exchanging p The value is ："<<*p<<"\t"<<"q The value is ："<<*q<<endl;
 	
 	cout<<endl;
 	a = 5,b = 10;
 	p = &a,q = &b; 
  	cout<<" Exchange before p The value of is ："<< p<<"\t"<<"q The value of is ："<<q<<endl;
 	cout<<" Exchange before p The value is ："<<*p<<"\t"<<"q The value is ："<<*q<<endl;
 	cout<<endl;
 	SwapPoint3(p,q); 
 	cout<<" After exchanging p The value of is ："<< p<<"\t"<<"q The value of is ："<<q<<endl;
 	cout<<" After exchanging p The value is ："<<*p<<"\t"<<"q The value is ："<<*q<<endl;
 	
 	return  0;
} 

Output ：

 Exchange before p The value of is ：0x66ff24 q The value of is ：0x66ff20
 Exchange before p The value is ：5    q The value is ：10

 After exchanging p The value of is ：0x66ff24 q The value of is ：0x66ff20
 After exchanging p The value is ：5    q The value is ：10

 Exchange before p The value of is ：0x66ff24 q The value of is ：0x66ff20
 Exchange before p The value is ：5    q The value is ：10

 After exchanging p The value of is ：0x66ff24 q The value of is ：0x66ff20
 After exchanging p The value is ：10   q The value is ：5

 Exchange before p The value of is ：0x66ff24 q The value of is ：0x66ff20
 Exchange before p The value is ：5    q The value is ：10

 After exchanging p The value of is ：0x66ff20 q The value of is ：0x66ff24
 After exchanging p The value is ：10   q The value is ：5
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