93 lines
2.1 KiB
C++
93 lines
2.1 KiB
C++
//
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// Created by light on 19-11-3.
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//
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#include <iostream>
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using namespace std;
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// non-explicit-one-argument ctor
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class Fraction
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{
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public:
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// non-explicit-one-argument ctor 可以把别的东西转换为Fraction这种
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Fraction(int num, int den = 1) : m_numerator(num), m_denominator(den) {}
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Fraction operator+(const Fraction &f)
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{
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return Fraction(this->m_numerator + f.m_numerator);
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}
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void getNumAndDen()
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{
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cout << m_numerator << " " << m_denominator << endl;
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}
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private:
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int m_numerator; // 分子
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int m_denominator; // 分母
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};
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// explicit-one-argument ctor
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class Fraction1
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{
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public:
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// explicit-one-argument ctor 可以把别的东西转换为Fraction这种
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explicit Fraction1(int num, int den = 1) : m_numerator(num), m_denominator(den) {}
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Fraction1 operator+(const Fraction1 &f)
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{
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return Fraction1(this->m_numerator + f.m_numerator);
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}
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void getNumAndDen()
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{
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cout << m_numerator << " " << m_denominator << endl;
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}
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private:
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int m_numerator; // 分子
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int m_denominator; // 分母
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};
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class P
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{
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public:
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P(int a, int b)
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{
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cout << "P(int a,int b)\n";
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}
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P(int a, int b, int c)
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{
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cout << "non-explicit P(int a,int b,int c)\n";
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}
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explicit P(int a, int b, int c, int d)
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{
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cout << "explicit P(int a,int b,int c,int d)\n";
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}
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};
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void fp(const P &)
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{
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}
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int main()
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{
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Fraction f(3, 5);
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Fraction ff = f + 3; // 会将3转换为(3,1) 隐式转换
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ff.getNumAndDen();
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// 如果不想编译器进行隐式转换,可以在前面添加explicit关键字
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// c++2.0之前explicit只禁止"存在单一实参"转换
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// c++2.0之后explicit可以进制"多个实参"转换
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// Fraction1 f1(3,5);
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// Fraction1 f2 = f1+3; // 会将3转换为(3,1) 不会隐式转换 error: no match for ‘operator+’ (operand types are ‘Fraction1’ and ‘int’)
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// f2.getNumAndDen();
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P p1 = {77, 5};
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P p2 = {77, 5, 89};
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// P p3 = {77, 5, 89,99}; //error: converting to ‘P’ from initializer list would use explicit constructor ‘P::P(int, int, int, int)’
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return 0;
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}
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