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C++運算子過載

一、運算子過載 C++中運算子過載允許將標準運算子運用在自己定義的類的物件,包括物件之間的運算等等。

二、運算子過載的型別 1、成員函式的過載 2、友緣函式的過載

三、運算子過載規則 1、不能有新的運算子 2、運算子過載後自身的優先順序以及結合規則不變 3、不能過載運算子有: 作用域解析運算子 :: 條件運算子 ?; 直接成員訪問運算子 . 運算子 sizeof

四、運算子過載特點 1、提高了程式碼的易讀性 2、也屬於一種函式呼叫方式 3、它的本質是函式的過載

五、實現基本的運算子過載


    #include<iostream>
    using namespace std;
    
    //初始化
    class CComplex
    {
    public:
		class CComplex()
			:_real(int()),_image(int())
		{}
		
		CComplex(int real, int image) 
			:_real(real), _image(image)
		{}
		
		//拷貝建構函式
		CComplex(const CComplex &src) 
			:_real(src._real), _image(src._image)
		{}

		//等號運算子的過載函式
		CComplex &operator=(const CComplex& src)
		{
			if (this == &src)
			{
				return *this;
			}
			_real = src._real;
			_image = src._image;
	
			return *this;
		}

		//+運算子的過載    (this,CComplex&)
		CComplex operator+(/*this,*/const CComplex& src)
		{
			return CComplex(_real + src._real, _image + src._image);
		}
	
		//+運算子的過載    (this,int)
		CComplex operator+(int a)
		{
			return CComplex(_real + a, _image);
		}

		//	-運算子的過載    (this,CComplex&)
		CComplex operator-(const CComplex& src)
		{
			return CComplex(_real - src._real, _image - src._image);
		}

		//	-運算子的過載    (this,int)
		CComplex operator-(int a)
		{
			return CComplex(_real - a, _image);
		}

		//輸出運算子的過載
		ostream& operator<<(/*this,*/ostream &out)//cout<<c3
		{
			out << _real << " ";
			out << _image << " ";
			return out;
		}

		//輸入運算子的過載
		istream& operator>>(istream& in)
		{
			in >> _real;
			in >> _image;
			return in;
		}

		//前置++ 
		const CComplex &operator++(/*this*/)
		{
			++_real;
			++_image;
			return *this;
		}

		//後置++
		const CComplex operator++(int)
		{                    //10      15
			return CComplex(_real++, _image++);//CComplex(10,15)
		}

		//前置--
		const CComplex &operator--()
		{
			--_real;
			--_image;
			return *this;
		}

		//後置--
		const CComplex operator--(int)
		{
			return CComplex(_real--,_image--);//這裡返回的是一個臨時量
		}
		//臨時量是一個常量,不可以修改

		bool operator==(const CComplex& src)
		{
			return (_real == src._real && _image == src._image);
		}
				
		void show()
		{
			cout << _real << " " << _image << endl;
		}
	
private:
		int _real;
		int _image;

		friend CComplex operator+(int a, const CComplex& src);
		friend CComplex operator-(int a, const CComplex& src);
		friend ostream& operator<<(ostream & out, const CComplex &src);
		friend istream& operator>>(istream& in, CComplex &src);
};
 
//+ 運算子的過載    (int,CComplex)
CComplex operator+(int a, const CComplex& src)
{
	return CComplex(src._real + a, src._image);
}

//- 運算子的過載    (int,CComplex)
CComplex operator-(int a, const CComplex& src)
{
	return CComplex(a - src._real, src._image);
}

//輸出運算子過載
ostream& operator<<(ostream & out, const CComplex &src)
{
	out << src._real << " ";
	out << src._image << " ";
	return out;
}

//輸入運算子過載
istream& operator>>(istream & in,  CComplex &src)
{
	in>>src._real;
	in>>src._image;
	return in;
}