IDE Qt Creator 4.0.3
stock.h

#ifndef STOCK_H
#define STOCK_H#include <string>class Stock  //类声明
{
private:std::string company;long shares;  //double share_val;double total_val;void set_tot(){total_val=share_val*shares;}
public:Stock(); //默认构造函数Stock(const std::string &co,long n=0,double pr=0.0);  //构造函数~Stock();  //析构函数void acquire(const std::string &co,long n,double pr);  //获得股票void buy(long num,double price);  //买入股票void sell(long num,double price);  //卖出股票void update(double price);  //更新股票价格void show();  //显示关于所持股票的信息
};#endif // STOCK_H

main.cpp

#include <iostream>
#include "stock.h"using namespace std;
//默认构造函数
Stock::Stock()
{cout<<"Default constructor called\n";company="no name";shares=0;share_val=0.0;total_val=0.0;
}
//构造函数
Stock::Stock(const string &co, long n, double pr)
{cout<<"Construcor using"<<co<<" called\n";company=co;if(n<0){cout<<"Number of shares can't be negative;"<<company<<"shares set to 0\n";shares=0;}else{shares=n;}share_val=pr;set_tot();
}
//析构函数
Stock::~Stock()
{cout<<"bye,"<<company<<endl;
}
//对某个公司股票的首次购买
void Stock::acquire(const string &co, long n, double pr)
{company=co;if(n<0){cout<<"Number of shares can't be negative;"<<company<<"shares set to 0.\n";}else{shares=n;}share_val=pr;set_tot();
}
//购买股票
void Stock::buy(long num, double price)
{if(num<0){cout<<"Number of shares purchased can't be negative."<<"Transaction is aborted.\n";}else{shares+=num;share_val=price;set_tot();}
}
//减少持有的股票
void Stock::sell(long num, double price)
{if(num<0){cout<<"Number of shares sold cna't be negative."<<"Transaction is aborted.\n";}else if(num>shares){cout<<"You can't sell more than you have!"<<"Transaction is aborted.\n";}else{shares-=num;share_val=price;set_tot();}
}
//
void Stock::update(double price)
{share_val=price;set_tot();
}
void Stock::show()
{ios_base::fmtflags orig=cout.setf(ios_base::fixed,ios_base::floatfield);std::streamsize prec=cout.precision(3);cout<<"Company:"<<company<<" Shares:"<<shares<<'\n';cout<<" Shares Price:$"<<share_val;cout.precision(3);cout<<" Total Worth:$"<<total_val<<'\n';//show()应重置格式信息，使其恢复到自己被调用前的状态cout.setf(orig,ios_base::floatfield);cout.precision(prec);
}
int main(int argc, char *argv[])
{{cout<<"Using constructos to create new objects\n";Stock stock1("NanoSmart",12,20.0);stock1.show();Stock stock2=Stock("Boffo Objects",2,2.0);stock2.show();cout<<"Assigning stock1 to stock2:\n";stock2=stock1;stock1.show();stock2.show();cout<<"Using a constructor to reset an object\n";stock1=Stock("Nifty Foods",10,50.0);  //临时对象stock1.show();cout<<"Done\n";}return 0;
}

运行结果如下