stock2.cpp

一本很好的C++学习的丛书！初学者必看的

// stock2.cpp -- improved version
#include <iostream>
#include "stock2.h"

// constructors
Stock::Stock()        // default constructor
{
    std::strcpy(company, "no name");
    shares = 0;
    share_val = 0.0;
    total_val = 0.0;
}

Stock::Stock(const char * co, int n, double pr)
{
    std::strncpy(company, co, 29); 
    company[29] = '\0';

    if (n < 0)
    {
        std::cerr << "Number of shares can't be negative; "
                   << company << " shares set to 0.\n";
        shares = 0;
    }
    else
        shares = n;
    share_val = pr;
    set_tot();
}

// class destructor
Stock::~Stock()        // quiet class destructor
{
}

// other methods
void Stock::buy(int num, double price)
{
     if (num < 0)
    {
        std::cerr << "Number of shares purchased can't be negative. "
             << "Transaction is aborted.\n";
    }
    else
    {
        shares += num;
        share_val = price;
        set_tot();
    }
}

void Stock::sell(int num, double price)
{
    using std::cerr;
    if (num < 0)
    {
        cerr << "Number of shares sold can't be negative. "
             << "Transaction is aborted.\n";
    }
    else if (num > shares)
    {
        cerr << "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() const
{
    using std::cout;
    using std::endl;
    cout << "Company: " << company
        << "  Shares: " << shares << endl
        << "  Share Price: $" << share_val
        << "  Total Worth: $" << total_val << endl; 
}

const Stock & Stock::topval(const Stock & s) const
{
    if (s.total_val > total_val)
        return s;
    else
        return *this; 
}