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。