C++重载

原创于 2018-11-03 10:32:04 发布 · 213 阅读

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本文探讨了在C++中实现货币类的输出重载方法，通过两种方式：一是将重载放置于类内部，二是将其设为友元函数在类外实现，解决了私有成员访问的问题。

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//实现<<重载         在类内的output是因为重载的不能直接获取private内容
void currency::output(ostream& out)const {//把货币值插入流out
    long theAmount = amount;
    if (theAmount < 0) {
        out << '-';
        theAmount = -theAmount;
    }
    long dollars = theAmount / 100;
    out << '$' << dollars << '.';
    int cents = theAmount - dollars * 100;
    if (cents < 10)
        out << '0';
    out << cents;
}
ostream& operator<<(ostream& out, const currency& x)
{
    x.output(out);
    return out;
}


//法二
//在类内设为友元函数

//类外情况
ostream& operator<<(ostream& out, const currency& x)
{
    long theAmount = amount;
    if (theAmount < 0) {
        out << '-';
        theAmount = -theAmount;
    }
    long dollars = theAmount / 100;
    out << '$' << dollars << '.';
    int cents = theAmount - dollars * 100;
    if (cents < 10)
        out << '0';
    out << cents;

    return out;
}