class CBook{
public:
  static double price;//需要通過類外來進(jìn)行初始化
}

int main(void){

  CBook book;
  book.price;//通過對(duì)象來訪問
  CBook::price//通過類名來訪問

  return 0;
}

class CBook{
public:
  static double price;
  CBook book;//非法定義，不允許在該類中定義所屬類的對(duì)象
  static CBook m_book;//正確
  CBook *book;//正確
};

class CBook{
public:
  int pages;
  static double price;

  //定義一個(gè)函數(shù)，以靜態(tài)數(shù)據(jù)作為默認(rèn)參數(shù)
  void outPutInfo(int data = price){
    //實(shí)現(xiàn)
  }

  //錯(cuò)誤定義，普通數(shù)據(jù)不能作為默認(rèn)參數(shù)
  void outPutPage(int data = pages){
    //實(shí)現(xiàn)
  }
};

static void outPut();

static void outPut() const;//錯(cuò)誤定義

//錯(cuò)誤的定義
static void CBook::outPutInfo(){
  //實(shí)現(xiàn)
}

class CBook{

public:
  int pages;
  void outputPages(){
    cout<<pages<<endl;
  }
};

int main(){
  CBook book1,book2;
  book1.pages = 10;
  book2.pages = 20;
  book1.outputPages();
  book2.outputPages();
  return 0;
}

//函數(shù)調(diào)用
book1.outputPages(&book1);

//函數(shù)實(shí)現(xiàn)
void outputPages(CBook *this){//隱含的this指針
  cout<<this->pages<<endl;//使用this指針訪問數(shù)據(jù)成員
}

/**
 * 本示例為了說明this的三種用法！
 */
package test;
public class ThisTest {
  private int i=0;

  ThisTest(int i){
    //(1)this.i表示成員變量i，i表示參數(shù)
    this.i=i+1;
  }

  ThisTest(String s){
    System.out.println("String constructor: "+s);
  }

  ThisTest(int i,String s){
    //(2)this調(diào)用第二個(gè)構(gòu)造器
    this(s);

    this.i=i++;
  }
  public ThisTest increment(){
    this.i++;
    //(3)返回的是當(dāng)前的對(duì)象
    return this;
  }
  public static void main(String[] args){
    ThisTest tt0=new ThisTest(10);
    ThisTest tt1=new ThisTest("ok");
    ThisTest tt2=new ThisTest(20,"ok again!");

    System.out.println(tt0.increment().increment().increment().i);
  }
}