写过的真正意义上的第一个C++程序

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By YANQUN | Published: 二月 24, 2008 | Edit

 

记得当时刚过完年回到学校，看了一个寒假的书，迫不及待的想实践一下，于是参照《Exceptional C++》上面反复拿出来举例的Complex类，自己重新写了一个，虽然不是独创的。首先规划好了想要实现哪些接口，然后一条一条地到《C++ Primer》中去找相应的注意事项和一般约定。整个代码几乎是自己独立写出的。后来在面试过程中，还重新将这份代码又写了一遍提交给考官，呵呵，当时给他的感觉估计还好，但是他哪知道我只会这几行代码 :-)

 

感觉现在写代码的风格几乎都是那个时候定型的。喜欢比较整洁的风格，看到乱七八糟的代码总有重构的冲动。

#include <iostream>
using namespace std;

class Complex
{
public:
    Complex()
    {
    }//无形参的构造函数
    Complex(double _r, double _i = 0) : _real(_r), _img(_i)
    {
    }//constructor fun.
    Complex(const Complex&);//copy constructor fun.
    Complex& operator=(const Complex&);//赋值操作符
    Complex& operator+=(const Complex&);
    Complex& operator-=(const Complex&);
    Complex& operator*=(const Complex&);
    Complex& operator/=(const Complex&);//复合赋值操作符
    Complex& operator++(); //前缀式的自增操作符
    Complex operator++(int);//后缀式
    Complex& operator–();
    Complex operator–(int);
    ostream& ops(ostream&) const;
    istream& ips(istream&);//输入操作需要更改类的数据，其辅助函数就不能定义为const的
    ~Complex()
    {
    }
private:
    double _real, _img;
};

//定义赋值操作符
Complex& Complex::operator=(const Complex& cr)
{
    this->_real = cr._real;
    this->_img = cr._img;
    return *this;
}

//定义输入输出操作
ostream& Complex::ops(ostream& os) const
{
    if (_img > 0)
    {
        return os << _real << " + " << _img << "i";
    }
    else if (_img == 0)
    {
        return os << _real;
    }
    else
    {
        return os << _real << " + " << "(" << _img << ")" << "i";
    }
}

ostream& operator<<(ostream& os, const Complex& cr)
{
    return cr.ops(os);
    //借助于类的成员函数来实现操作符函数访问私有数据。
    //由于这里是常引用，辅助的成员函数也应定义为const成员函数。
}

istream& Complex::ips(istream& os)
{
    return os >> _real >> _img;
}

istream& operator>>(istream& os, Complex& cr)
    //注意这里需要改变形参cr，因此不能将其定为const
{
    return cr.ips(os);
    //只有非const的对象才能调用非const的成员函数。
}

//定义复制构造函数
Complex::Complex(const Complex& rhs)
{
    _real = rhs._real;
    _img = rhs._img;
    //注意这里直接访问类中的数据成员，而不是通过对象来调用
}

//定义相应的复合赋值运算
Complex& Complex::operator+=(const Complex& cl)
{
    _real += cl._real;
    _img += cl._img;
    return *this;
}

Complex& Complex::operator-=(const Complex& cl)
{
    _real -= cl._real;
    _img -= cl._img;
    return *this;
}

Complex& Complex::operator*=(const Complex& cl)
{
    double _t = _real;
    _real = (_real * cl._real – _img * cl._img);
    _img = (_t * cl._img + _img * cl._real);
    return *this;
}

Complex& Complex::operator/=(const Complex& cr)
{
    double _r = _real, _i = _img, _m = cr._real* cr._real + cr._img* cr._img;
    if (_m == 0)
        cout << "Error" << endl;
    else
    {
        _real = (_r * cr._real + _i * cr._img) / _m;
        _img = (-_r * cr._img + _i * cr._real) / _m;
    }
    return *this;
}

//利用复合赋值操作来实现四则远算
Complex operator+(const Complex& cl, const Complex& cr)
{
    return Complex(cl) += cr;
}

Complex operator-(const Complex& cl, const Complex& cr)
{
    return Complex(cl) -= cr;
}

Complex operator*(const Complex& cl, const Complex& cr)
{
    return Complex(cl) *= cr;
}

Complex operator/(const Complex& cl, const Complex& cr)
{
    return Complex(cl) /= cr;
}

//先定义前缀式的，后缀式根据此操作实现
Complex& Complex::operator++()
{
    ++_real;
    return *this;
}

Complex Complex::operator++(int)
{
    Complex _ct(*this);
    ++(*this);
    return _ct;
}

Complex& Complex::operator--()
{
    --_real;
    return *this;
}

Complex Complex::operator--(int)
{
    Complex _ct(*this);
    --(*this);
    return _ct;
}

int main()
{
    Complex c1(2, 1), c2(4, 3);
    Complex c0 = 0;
    Complex c4(c1);
    Complex c5(2.4, 3.5);
    c5 *= c2;
    Complex c6;
    Complex c3 = c1 + c2;
    cout << "c1: " << c1 << endl;
    cout << "c2: " << c2 << endl;
    cout << "c3: " << c3 << endl;
    cout << "c4: " << c4 << endl;
    cout << "c5: " << c5 << endl;
    cout << "c5++: " << c5++ << endl;
    cout << "c5: " << c5 << endl;
    cout << "++c5: " << ++c5 << endl;
    cout << "--c5: " << --c5 << endl;
    cout << "c5: " << c5 << endl;
    cout << "c2/c1: " << c2 / c1 << endl;
    cout << "c1*c2: " << c1 * c2 << endl;
    cout << "c2-c1: " << c2 - c1 << endl;
    cout << "c5+c1: " << c5 + c1 << endl;
    cout << "Please input c6: ";
    cin >> c6;
    cout << "c6: " << c6 << endl;
    return 0;
}