C++ Constructor

// File: test.cpp
// Author: lxw
// Date: 2015-08-11

#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <set>
#include <climits>

using namespace std;

int number(){
    cout << "hello" << endl;
    return 11;
}

class Demo{
private:
    int a = number();   //NOTE: [calls before constructor.] NOT ALWAYS call this.
    int b = number();
public:
    Demo(){
        cout << "Constructor Demo()" << endl;
    }
    Demo(int A):a(A){
        cout << "Constructor Demo(int A)" << endl;
    }
    int getA(){
        return this->a;
    }
    int getB(){
        return this->b;
    }
};

int main(void){
    /*
    //NOTE: NOT "hello\nConstructor Demo(int A)" but "Constructor Demo(int A)"
    Demo d(3);  //Constructor Demo(int A)
    cout << d.getA() << endl; //3    
    cout << endl;
    Demo d1;  //hello\nConstructor Demo()
    cout << d1.getA() << endl;  //11
    */
    /*
    Output:
    Constructor Demo(int A)
    3

    hello
    Constructor Demo()
    11
    */

    Demo d(3);  //hello\nConstructor Demo(int A)
    cout << d.getA() << endl; //3
    cout << d.getB() << endl; //11
    cout << endl;
    Demo d1;  //hello\nhello\nConstructor Demo()
    cout << d1.getA() << endl;  //11
    cout << d1.getB() << endl;  //11
    /*
    Output:
    hello
    Constructor Demo(int A)
    3
    11

    hello
    hello
    Constructor Demo()
    11
    11
    */
    return 0;
}