0 前言

1 内置类型

2 自定义类型

3 结论

4 源码

• case2: (k = j) = i

• case1: p3 = p2 = p1

• • 不返回引用的People

　　　　　　p3 == p1

• case2: (p3 = p2) = p1

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include string>
#include 
#include 

#include 
#include using std::cout;
using std::endl;
using std::string;
using std::vector;
using std::stringstream;

void test_int()
{
  cout "test_int()"  endl;
  int i = 1, j = 2, k = 3;

  k = j = i;

  cout "\ti=" // 1
  cout "\tj=" // 1
  cout "\tk=" // 1
}

void test_int2()
{
  cout "test_int2()"  endl;
  int i = 1, j = 2, k = 3;

  (k = j) = i;

  cout "\ti=" // 1
  cout "\tj=" // 2
  cout "\tk=" // 1
}

class People
{
 public:
  People(const string &_name = "")
      : name(_name)
  {}

  People operator=(const People &_p)
  {
    name = _p.name;
    return *this;
  }

  string name;
};

void test()
{
  cout "test(): not reference"  endl;
  cout "\tp3=p2=p1"  endl;
  People p1("p1"), p2("p2"), p3("p3");

  p3 = p2 = p1;
  
  cout "\t\tp2.name=" // p1
  cout "\t\tp3.name=" // p1
}

void test2()
{
  cout "test2(): not reference"  endl;
  cout "\t(p3=p2)=p1"  endl;
  People p1("p1"), p2("p2"), p3("p3");

  (p3 = p2) = p1;
  
  cout "\t\tp2.name=" // p2
  cout "\t\tp3.name=" // p2
}

class PeopleRef
{
 public:
  PeopleRef(const string &_name = "")
      : name(_name)
  {}

  PeopleRef& operator=(const PeopleRef &_p)
  {
    name = _p.name;
    return *this;
  }

  string name;
};

void test_ref()
{
  cout  endl;
  cout "test_ref(): reference"  endl;
  cout "\tp3=p2=p1"  endl;
  PeopleRef p1("p1"), p2("p2"), p3("p3");;

  p3 = p2 = p1;

  cout "\t\tp2.name=" // p1
  cout "\t\tp3.name=" // p1
}

void test_ref2()
{
  cout "test_ref2(): reference"  endl;
  cout "\t(p3=p2)=p1"  endl;
  PeopleRef p1("p1"), p2("p2"), p3("p3");;

  (p3 = p2) = p1;

  cout "\t\tp2.name=" // p2
  cout "\t\tp3.name=" // p1
}

class PeopleDefault
{
 public:
  PeopleDefault(const string &_name = "")
      : name(_name)
  {}

  string name;
};

void test_default()
{
  cout  endl;
  cout "test_default()"  endl;
  cout "\tp3=p2=p1"  endl;
  PeopleDefault p1("p1"), p2("p2"), p3("p3");

  p3 = p2 = p1;
  
  cout "\t\tp2.name=" // p1
  cout "\t\tp3.name=" // p1
}

void test_default2()
{
  cout "test_default2()"  endl;
  cout "\t(p3=p2)=p1"  endl;
  PeopleDefault p1("p1"), p2("p2"), p3("p3");

  (p3 = p2) = p1;
  
  cout "\t\tp2.name=" // p2
  cout "\t\tp3.name=" // p1
}

int main ()
{
  test_int();
  test_int2();
  
  test();
  test2();
  
  test_ref();
  test_ref2();

  test_default();
  test_default2();
}