使用非成员函数(non-member)处理函数的所有参数都需要类型转换
本文地址: http://blog.csdn.net/caroline_wendy/article/details/24309293
有些函数, 所有参数都需要使用类型转换, 比如乘法, 写一个有理数类Rational, 需要执行乘法操作:
函数满足: Rational = Rational*double; Rational = double*Rational; 则需要使用非成员函数(non-member);
成员函数的发起者必须是类, 因为可能出现double类型在前的情况, 则无法执行乘法, 所以应使用非成员函数;
执行时: 即Rational = Rational*Rational(double); Rational = Rational(double)*Rational, 发生了隐式转换.
代码:
/*
* test.cpp
*
* Created on: 2014.04.22
* Author: Spike
*/
/*eclipse cdt, gcc 4.8.1*/
#include <iostream>
//有理数
class Rational {
public:
Rational(double numerator = 0, double denominator = 1) :
m_n(numerator), m_d(denominator) {}
double numerator() const {return m_n;};
double denominator() const {return m_d;};
double value() {return (m_n/m_d);}
private:
double m_n;
double m_d;
};
const Rational operator* (const Rational& lhs,
const Rational& rhs) {
return Rational(lhs.numerator()*rhs.numerator(),
lhs.denominator()*rhs.denominator());
}
int main(void) {
Rational oneFourth(1, 4);
Rational result;
result = oneFourth * 3.5;
result = 3.5 * oneFourth;
std::cout << "result = " << result.value() << std::endl;
return 0;
}
输出:
result = 0.875