11/3c++程序清单10.4,10.5,10.6

最新推荐文章于 2025-02-14 10:56:04 发布

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最新推荐文章于 2025-02-14 10:56:04 发布

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本文链接：https://blog.youkuaiyun.com/qq_34600560/article/details/83690888

本文深入探讨了C++中股票类的构造函数使用及对象赋值过程，展示了如何通过构造函数创建和初始化对象，以及赋值操作的影响。通过具体代码示例，解释了对象赋值实际上是值的传递，而非地址操作。

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#include “stdafx.h”
#include
#include “stock10.h”//usestock.cpp
int main()
{ {using std::cout;
cout << “using constructors to create new objects\n”;
Stock stock1(“nanosmart”, 12, 20.0);
stock1.show();
Stock stock2 = Stock(“boffo object”, 2, 2.0);
stock2.show();
cout << “assigning stock1 and stock2:\n”;
stock2 = stock1;
cout << “listing stock1 and stock2:\n”;
stock1.show();
stock2.show();
cout << “using a constructor to reset an object\n”;
stock1 = Stock(“nifty foods”,10,50.0);
cout << “revised stock1:\n”;
stock1.show();
cout << “done”;
stock2.show();
}
system(“pause”);
return 0;
}

/////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
#ifndef STOCK10_H//stock10.h
#define STOCK10_H
// !STOCK10_H
#include
class Stock
{
private:std::string company;
long shares;
double total_val;
double share_val;
void set_tot() { total_val = shares*share_val; }
public:Stock();
Stock(const std::string &co, long n = 0, double pr = 0.0);
~Stock();
void buy(long num, double price);
void sell(long num, double price);
void update(double price);
void show();
};
#endif
/////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
#include “stdafx.h”
#include//stock10.cpp
#include “stock10.h”
Stock::Stock()
{
std::cout << “default constructor called\n”;
company = "no name ";
shares = 0;
share_val = 0.0;
total_val = 0.0;
}
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”;
shares = 0;

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

}
Stock::~Stock()
{
std::cout << “bye,” << company << “!\n”;
}
void Stock ::buy(long num,double price)
{
if (num < 0) { std::cout << “number of shares purchased can’t be negative.”<<“transaction is aborted”;
}else
{
shares += num;
share_val = price;
set_tot();
}
}
void Stock ::sell(long num,double price )
{
using std::cout;
if (num<0)
{
cout << “number of shares sold can’t be negtive.” << “transactionis 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()
{
using std::cout;
using std::ios_base;
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 .setf(orig, ios_base::floatfield);
cout.precision(prec);
}
/////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
在这里插入图片描述和昨天一样，我发现，同一个类的对象赋值，其实就是传递了值而已，和地址没有半毛钱关系，看最后的stock2.show()就可知了，其实so easy ,但是打的时候不小心赋值时候=，Stock都漏掉过，怪不得会报错说double 类型不能赋值给stock类型，亲爱的你，可不要犯错哦，其实犯了也无所谓，反正还能改，我们可是编程的粉刷匠