const keyword feature analysis (to be added)

const keyword

/***********************c++ Const characteristic Analysis *********************/
#include <iostream>

using namespace std;

Class a{
private:
	int A;
Public:
	A () {}
	a (int A) {a::a = A;}
	void SetA (const int& a) {
		a::a = A;
	}
	The const plus at the end indicates that the member function does not change the member variable in the class
	int geta () const{return
		A;
	}
	The return value is the const
	const a&
	operator= (const a& A0) {
		A = a0.a;
		return *this;
	}
;


int main () {
	//1. The value that the pointer points to cannot be changed
	const int* a1 = new int (1);
	cout << "*A1:" << *a1 << Endl;

	2. The value of the pointer itself cannot be changed
	int* const A2 = new int (2);
	cout << "*A2:" << *a2 << Endl;

	2. The value that the pointer points to can change
	*A2 =;
	cout << "*A2:" << *a2 << Endl;

	A A1;
	A A2;
	A A3;
	A1. SetA (3);
	If written (A2 = A3) = A1 will cause an error because the return value of the overloaded equal sign is const
	A2 = A3 = A1;
	cout << "A2. Geta (): "<< A2. Geta ();

	return 0;
}

Output: