关于析构函数和构造函数何时调用的小例子

详情见C++ PrimerPlus第十章

省略其他函数，将构造函数和析构函数写出来

Stock::Stock() //default constructor{    std::cout<<"Default constructor called\n";    company="no name";    shares=0;    share_val=0;    total_val=0;}

Stock::Stock(const std::string&co,long n,double pr){    std::cout<<"Constructor using"<<co<<"called\n";    company=co;    if(n<0)    {        std::cout<<"Number of shares can‘t be negative;"<<company<<"shares set to 0.\n";

}    else    {        shares=n;    }    share_val=pr;    set_tot();}

Stock::~Stock(){    std::cout<<"Bye,"<<company<<"!\n";}

正常情况下析构函数和构造函数一般没有cout语句，这里为了显示出他何时被调用，加上了输出语句。

int main(){    {        using std::cout;        cout<<"Using constructors to creat new objects\n";        Stock stock1("NankSmart",12,20);        stock1.show();        Stock stock2("Boffo Objects",2,2);//调用时        // 直接调用了构造函数 即下列函数

/*Stock::Stock(const std::string&co,long n,double pr){    std::cout<<"Constructor using"<<co<<"called\n";    company=co;    if(n<0)    {        std::cout<<"Number of shares can‘t be negative;"<<company<<"shares set to 0.\n";

}    else    {        shares=n;    }    share_val=pr;    set_tot();}  因此编译后有如下语句：  Constructor usingBoffo Objectscalled  Company: Boffo Objects shares: 2  Share price: 2.000 total worth :4.00         * */

　　　　　stock2.show();

cout<<"Assigning stock1 to stock2 :\n";        stock2=stock1;        cout<<"Listening stock1 and stock2: \n";        stock1.show();        stock2.show();

cout<<"Using a constructor to reset an object\n";        stock1=Stock("Nifty Foods",10,50);        //这里调用了析构函数，有如下语句 "Bye,Nifty Foods!"        cout<<"Revised stock1:\n";        stock1.show();        cout<<"Done\n";        //最后结束的时候，全部对象结束调用，所以有调用了两个对象的析构函数        //有如下语句        //Bye,NankSmart!        //Bye,Nifty Foods!    }}最后是编译后的结果（有些遍以前可能不同）

Using constructors to creat new objects
Constructor usingNankSmartcalled
Company: NankSmart shares: 12
Share price: 20.000 total worth :240.00
Constructor usingBoffo Objectscalled
Company: Boffo Objects shares: 2
Share price: 2.000 total worth :4.00
Assigning stock1 to stock2 :
Listening stock1 and stock2:
Company: NankSmart shares: 12
Share price: 20.000 total worth :240.00
Company: NankSmart shares: 12
Share price: 20.000 total worth :240.00
Using a constructor to reset an object
Constructor usingNifty Foodscalled
Bye,Nifty Foods!
Revised stock1:
Company: Nifty Foods shares: 10
Share price: 50.000 total worth :500.00
Done
Bye,NankSmart!
Bye,Nifty Foods!

Process finished with exit code 0