对构造函数、拷贝构造函数和赋值操作符调用的简单回顾

本文只是测试构造函数、拷贝构造函数和赋值操作符的调用问题，不涉及这些函数内的具体实现，所以多包涵
还有如果觉得有不足之处还望指出，谢谢…………

Cpp代码
#include<iostream>

using namespace std;

class Object{

char* name;
public:
Object()
{
cout << "Objected is constructed.(无参数)" << endl;
}

Object(char* s) //
{
name = s;//
cout << "Objected is constructed.(参数)" << endl;
}

Object( const Object& o)
{
//为对象申请内存并进行出错检查;(本文没有处理)
//从对象o复制到本对象
name = o.name;
cout << "Object is copied." << endl;
}

char* getName()
{
return name;
}
Object & operator = (const Object& lala)
{
name = lala.name;
cout << "Object is operator =." << endl;

return *this;
}

~Object()
{
cout << "Object is destructed." << endl;
}

};

Object getObject( Object o)
{
cout << "getO" << endl;//

return o;
}

Object getObject1( Object& o)
{
cout << "getO1" << endl;//

return o;
}

Object& getObject2( Object& o)
{
cout << "getO2" << endl;//

return o;
}

int main()
{

Object o("zhangsan");

Object o1;
o1 = getObject( o);
cout << endl;

cout << "Object o2 = getObject(o):" << endl;
Object o2 = getObject(o);//相当于Object o2(getObject(o));
cout << endl;

cout << "o1 = getObject(o):" << endl;
o1 = getObject(o);
cout << endl << endl;

//getObject1
cout << "getObject1:" << endl;
Object o11;
o11 = getObject1( o);
cout << endl;

cout << "Object o22 = getObject(o):" << endl;
Object o22 = getObject1(o);
cout << endl;

cout << "o11 = getObject(o):" << endl;
o11 = getObject(o);
cout << endl << endl;

//getObject2
cout << "getObject2:" << endl;
Object o111;
o111 = getObject2( o);
cout << endl;

cout << "Object o222 = getObject(o):" << endl;
Object o222 = getObject2(o);
cout << endl;

cout << "o111 = getObject(o):" << endl;
o111 = getObject(o);

cout << "end" << endl;

return 0;
}

Objected is constructed.(参数)
Objected is constructed.(无参数)
Object is copied.           //每次传参都会构建临时对象
getO
Object is copied.
Object is destructed.
Object is operator =.
Object is destructed.

Object o2 = getObject(o):
Object is copied.
getO
Object is copied.
Object is destructed.

o1 = getObject(o):
Object is copied.
getO
Object is copied.
Object is destructed.
Object is operator =.
Object is destructed.

getObject1:
Objected is constructed.(无参数)
getO1
Object is copied.
Object is operator =.
Object is destructed.

Object o22 = getObject(o):
getO1
Object is copied.

o11 = getObject(o):
Object is copied.
getO
Object is copied.
Object is destructed.
Object is operator =.
Object is destructed.

getObject2:
Objected is constructed.(无参数)
getO2
Object is operator =.

Object o222 = getObject(o):
getO2
Object is copied.

o111 = getObject(o):
Object is copied.
getO
Object is copied.
Object is destructed.
Object is operator =.
Object is destructed.
end

拷贝构造函数和赋值操作符：
同样是利用现有对象的值，生成/更新另一个对象的值。
区别在于：拷贝构造函数是去完成对未初始化的存储区的初始化，而赋值操作符则是处理一个已经存在的对象。对一个对象赋值，当它一次出现时，它将调用拷贝构造函数，以后每次出现，都调用赋值操作符。

定义对象a，并用另一个对象b对a进行初始化时，
若没有拷贝构造函数时，那么编译器会自动生成一个
T b(1);//假设对象b已经初始化
T a(b);//初始化阶段，调用拷贝构造函数
T c = b;//虽然使用了“=”，但是初始化阶段，仍调用拷贝构造函数
c = a; //因为对象c已经定义，所以此处调用赋值操作符重载函数。如果没有编译器会自动生成一个。