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"<
    
     <<"called\n";     company=co;     if(n<0)     {
          std::cout<<"Number of shares can't be negative;"<
     
      <<"shares set to 0.\n";     }     else     {
          shares=n;     }     share_val=pr;     set_tot(); } Stock::~Stock() {
      std::cout<<"Bye,"<
      
       <<"!\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"<
    
     <<"called\n";     company=co;     if(n<0)     {
          std::cout<<"Number of shares can't be negative;"<
     
      <<"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