currency类的建立

//currency类

#include<iostream>
using namespace std;

enum signType { p = 1, m = -1 };//枚举

class currency
{
    //enum signType { p, m };//枚举
public:
    //构造函数
    currency(signType theSign = p,
        unsigned long theDollors = 0,
        unsigned int theCents = 0);//如果此处有{}，则此处为构造函数的定义，如果没有则定义放在类外部
    //析构函数
    ~currency()
    {

    }
    void setValue(signType, unsigned long, unsigned long);
    void setValue(double);
    signType getSign();
    unsigned long getDollors();
    unsigned int getCents();
    currency add(const currency &)const;
    //此函数不改变传入的参数，所以有第一个const，此函数不改变调用此函数对象，所以有第二个const
    currency & increment(const currency &);
    void increment2(const currency &);
    //此函数不改变传入的参数，所以加const。但是改变了调用此函数的对象。
    void input();//输入值返回给调用对象
    currency percent(double x);//返回调用对象的占比x
    currency subtract(const currency& x);
    currency multiply(double x);//返回调用对象的x倍
    currency divide(double x);//返回调用对象的1/x倍
    friend ostream & operator <<(ostream & output, const currency & x);
private:
    /*
    成员变量的初始化有两种方式:
    1、列表初始化，是真正的初始化，效率高
    2、在构造函数体内赋值，不是真正的初始化，效率较慢
    常成员变量必须在构造函数的初始化列表中进行初始化
    静态变量只能在类外初始化，且不加关键字static
    */
    signType sign;
    unsigned long dollors;
    unsigned int cents;
};//此处的分号不能忘记
currency::currency(signType theSign, unsigned long theDollors, unsigned int theCents)
{
    setValue(theSign, theDollors, theCents);
}
void currency::setValue(signType theSign, unsigned long theDollors, unsigned long theCents)
{
    if (theCents > 99)
        throw("cent should be <99");
    sign = theSign;
    dollors = theDollors;
    cents = theCents;
}
void currency::setValue(double theAmount)
{
    if (theAmount > 0)
        sign = p;
    else
        sign = m;
    dollors = (unsigned long)theAmount;
    cents = (theAmount - dollors + 0.001) * 100;
}
signType currency::getSign()
{
    return (*this).sign;//注意this是一个指针，不能用this.sign，正确写法为this->sign或者(*this).sign，*比.优先级低，所以加（）
}
unsigned long currency::getDollors()
{
    return this->dollors;
}
unsigned int currency::getCents()
{
    return this->cents;
}
currency currency::add(const currency & x)const
{
    long a1, a2, a3;
    currency result;
    a1 = dollors * 100 + cents;
    if (sign == m)
        a1 = -a1;
    a2 = x.dollors * 100 + x.cents;
    if (x.sign == m)
        a2 = -a2;
    a3 = a1 + a2;
    if (a3 < 0)
    {
        result.sign = m;
        a3 = -a3;
    }
    else
    {
        result.sign = p;
    }
    result.dollors = a3 / 100;
    result.cents = a3 - result.dollors * 100;
    return result;
}
currency & currency::increment(const currency & x)
{
    *this = this->add(x);
    return *this;
}
void currency::increment2(const currency & x)
{
    long a1, a2, a3;
    a1 = dollors * 100 + cents;
    if (sign == m)
        a1 = -a1;
    a2 = x.dollors * 100 + x.cents;
    if (x.sign == m)
        a2 = -a2;
    a3 = a1 + a2;
    if (a3 < 0)
    {
        this->sign = m;
        a3 = -a3;
    }
    else
    {
        this->sign = p;
    }
    this->dollors = a3 / 100;
    this->cents = a3 - this->dollors * 100;
}
void currency::input()//输入值返回给调用对象
{
    double mon;
    cout << "请输入金额：";
    cin >> mon;
    if (mon < 0)
        sign = m;
    else
        sign = p;
    dollors = (unsigned long)mon;
    cents = (mon - dollors + 0.001) * 100;
}
currency currency::subtract(const currency& x)
{
    currency result;
    long a1, a2, a3;
    a1 = dollors * 100 + cents;
    if (sign == m)
        a1 = -a1;
    a2 = x.dollors * 100 + x.cents;
    if (x.sign == m)
        a2 = -a2;
    a3 = a1 - a2;
    if (a3 < 0)
        result.sign = m;
    else
        result.sign = p;
    if (a3 < 0)
        a3 = -a3;
    result.dollors = a3 / 100;
    result.cents = a3 - result.dollors * 100;
    return result;
}
currency currency::percent(double x)//返回调用对象的占比x
{
    currency result;
    result.sign = sign;
    double mon = (dollors * 100 + cents)*x / 100;
    result.dollors = mon / 100;
    result.cents = mon - result.dollors * 100;
    return result;
}
currency currency::multiply(double x)//返回调用对象的x倍
{
    currency result;
    double a;
    if (x > 0)
        result.sign = sign;
    else
    {
        if (sign == p)
            result.sign = m;
        else
            result.sign = p;
    }
    a = (dollors * 100 + cents)*x;
    result.dollors = a / 100;
    result.cents = a - result.dollors * 100;
    return result;
}
currency currency::divide(double x)//返回调用对象的x倍
{
    currency result;
    double a;
    if (x > 0)
        result.sign = sign;
    else
    {
        if (sign == p)
            result.sign = m;
        else
            result.sign = p;
    }
    a = (dollors * 100 + cents) / x;
    result.dollors = a / 100;
    result.cents = a - result.dollors * 100;
    return result;
}
ostream & operator <<(ostream & output, const currency & x)
{
    output << " sign: " << x.sign << " dollors: " << x.dollors << " cents: " << x.cents << endl;
    return output;
}
int main()
{
    //测试setValue(m,dollors,cents)
    currency c1;
    c1.setValue(p, 3, 52);
    cout << " c1 " << c1 << endl;
    //测试构造函数
    currency c2(m, 3, 52);
    //测试setValue(double)
    cout << " c2 " << c2 << endl;
    currency c3;
    c3.setValue(6.52);
    cout << " c3 " << c3 << endl;
    cout << " c3 " << c3.getSign() << c3.getDollors() << c3.getCents() << endl;
    //测试add
    currency c4;
    c4 = c4.add(c3);
    cout << " c4 " << c4 << endl;

    //测试increment
    currency c5;
    c5.increment(c1);
    cout << " c5 " << c5 << endl;

    //测试increment2
    currency c6;
    c6.increment2(c2);
    cout << " c6 " << c6 << endl;

    //测试默认构造函数
    currency c7;
    cout << " c7 " << c7 << endl;

    //测试input()
    c7.input();
    cout << " c7 " << c7 << endl;
    //测试减法
    currency c8 = c3.subtract(c1);
    cout << " c8 " << c8 << endl;
    //测试百分比
    c8 = c1.percent(64.3);
    cout << " c8 " << c8 << endl;
    //测试乘法
    c8 = c2.multiply(2.1);
    cout << " c8 " << c8 << endl;
    //测试除法
    c8 = c1.divide(3.2);
    cout << " c8 " << c8 << endl;

}