【cpp语言】基础-5

转换函数

class Fraction {
public:
    Fraction(int num, int den=1): m_numerator(num), m_denominator(den) {}   
    operator double() const {   //转换函数，可写多个转换函数
        return (double) (m_numerator / m_denominator);
    }
private:
    int m_numerator;    //分子
    int m_denominator;  //分母
}

如何调用：

Fraction f(3,5);
double d = 4+f; //调用operator double()将f转换为小数

non-explicit-one-argument ctor

class Fraction {
public:
    Fraction(int num, int den=1): m_numerator(num), m_denominator(den) {}   
    Fraction operator + (const Fraction& f) {   //操作符重载
        return (double) (m_numerator / m_denominator);
    }
private:
    int m_numerator;    //分子
    int m_denominator;  //分母
}

调用：

Fraction f(3,5);
double d = 4+f; //调用non-explicit ctor将4转换为Fraction，再执行+

上面的operator +和double两个函数不能同时存在，若同时存在编译器会报错

explicit-构造函数

class Fraction {
public:
    explicit Fraction(int num, int den=1): m_numerator(num), m_denominator(den) {}   
    Fraction operator + (const Fraction& f) {   //操作符重载
        return (double) (m_numerator / m_denominator);
    }
private:
    int m_numerator;    //分子
    int m_denominator;  //分母
}

智能指针

TODO