Discussion on the basic use and address of pointer in array object

Probe into the basic use and address of pointer in array object ：

This involves classes and objects 、 Pointer and operator overloading ：
You can refer to it before reading （ The asterisk represents the key ）：
* Further understanding and use of classes and objects
** Pointer and its application
C++ Pointer to unit learning summary （ To continue ）, Allocation strategy of storage space ,new and delete Operator ,const qualifier Structure （ To continue ）, enumeration
***C++ Operator overload of
Some contents needing attention ：
Assignment of pointer and use of address fetching character ：

 	int *p = (int*)&b;  // With a pointer p Pointing to the address b, Namely the b Assign the address to the pointer p
    cout<<" The pointer p Address to ："<<&(*p)<<endl;
   *p=a.b;  // Give the pointer p assignment , Now pointer p It points to the address b, Therefore, it is equivalent to b=a.b;

Operator overloading ：

  A& operator=(const A &a){
    
        cout<<" heavy load "<<endl;
     	b=a.b;
        c=a.c;
        return *this;
    };

For operator overloading, please refer to ：
***C++ Operator overload of
This part is still very interesting （ The term operator overloading basically refers to C/C++, because Java Operator overloading is not supported , Programmers cannot define + * Equal operator , There is no right for programmers to overload operators . This is also taking into account Java Object oriented programming in （OOP） A matter of principle ）, Here is the function call operator in operator overloading （） Some examples of ：
Patients with a ：

// This example refers to the rookie tutorial ：https://www.runoob.com/cplusplus/function-call-operator-overloading.html
#include <iostream>
using namespace std;

class Distance
{
    
   private:
      int feet;             // 0  To infinity 
      int inches;           // 0  To  12
   public:
      //  The required constructor 
      Distance(){
    
         feet = 10;
         inches = 20;
      }
      Distance(int f, int i){
    
         feet = f;
         inches = i;
      }
      //  Overloading function call operators 
      Distance operator()(int a, int b, int c)
      {
    
         Distance D;  // Define a Distance  Call the default constructor to initialize , here feet=10,inches=20;
         cout<<" heavy load ：\t D.displayDistance(): \t";
         D.displayDistance();
         //  Perform random calculations （ Reassign ）
         D.feet = a + c + 10;
         D.inches = b + c + 100 ;
         return D;
      }
      //  The way to show the distance 
      void displayDistance()
      {
    
         cout << "F: " << feet <<  " I:" <<  inches << endl;
      }

};
int main()
{
    
   Distance D1(11, 10), D2;

   cout << "First Distance : ";
   D1.displayDistance();

   D2 = D1(10, 10, 10); // invoke operator()
   cout << "Second Distance :";
   D2.displayDistance();

   return 0;
}

Example 2 ：

#include <iostream>
using namespace std;
// Function object with state , Set different output stream objects and separators 
class PrintString{
    
	ostream &os;
	char sep;
public:
	PrintString(ostream &o = cout, char c = '\t')
: os(o), sep(c){
    }
	void operator()(const string& str){
    os << str << sep; }
};
int main(){
    
	PrintString welcomeMsg;
	welcomeMsg("Welcome!");
	PrintString errMsg(cerr, '\n');
	errMsg("Error!");
	errMsg("Error!");
	return 0;
}

Probe into the basic use and address of pointer in array object ：

#include<iostream>
#include<stdio.h>
using namespace std;
class A{
    
    const int b;
    int c;
public:
    A():b(0){
    /*cout<<" Call default constructor "<<endl;*/};
    A(int b1,int c1):b(b1),c(c1){
    };
    void show(){
    
        cout<<b<<" "<<c<<endl;
    }

    A& operator=(const A &a){
    
        cout<<" heavy load "<<endl;
        cout<<"b The address of ："<<&b<<endl;
        int *p = (int*)&b;  // With a pointer p Pointing to the address b, Namely the b Assign the address to the pointer p
        cout<<" The pointer p Address to ："<<&(*p)<<endl;
        *p=a.b;  // Give the pointer p assignment , Now pointer p It points to the address b, Therefore, it is equivalent to b=a.b;
        //b=a.b;
        c=a.c;
        return *this;
    };

};

//A *a[100]; // The default constructor was not called , It just exists as a pointer 
A a[100];  // Call default constructor , Exist as the default object 
int main(){
    
    /* const int i=2; cout<<&i<<endl; int *p = (int*)&i; cout<<&(*p)<<endl; *p=10; cout<<i<<endl; */

    /* A a1 = A(100); a[0]=&a1; (*a[0]).show(); */
    //A a0 = A(i+100,i+120); // If defined in this way, it is to call the constructor directly , No overloading 
    A a0;  // This defines calling the default constructor , If the default object a0 If you make a reassignment modification, you call the overloaded constructor ：a0 = A(i+100,i+120);
    for(int i=0;i<10;i++){
    
        a0 = A(i+100,i+120);
        a[i]=a0;
        a[i].show();
    }
     return 0;
}

result：

At the same time, pay attention to the address ：