//【習3.4】  復數類。

public class Complex
{
    private double real,im;                //實部，虛部

    public Complex(double real, double im) //構造方法
    {
        this.real = real;
        this.im = im;
    }
    
    public Complex(double real)            //構造方法重載
    {
        this(real,0);
    }
    
    public Complex()
    {
        this(0,0);
    }
    
    public Complex(Complex c)              //拷貝構造方法
    {
        this(c.real,c.im);
    }
    
    public boolean equals(Complex c)       //比較兩個對象是否相等
    {
        return this.real==c.real && this.im==c.im;
    } 
    
    public String toString() 
    {
        return "("+this.real+"+"+this.im+"i)";
    }
    
    public void add(Complex c)             //兩個對象相加
    {                                      //改變當前對象，沒有返回新對象
        this.real += c.real;
        this.im += c.im;
    }
    
    public Complex plus(Complex c)         //兩個對象相加，與add()方法參數一樣不能重載
    {                                      //返回新創建對象，沒有改變當前對象
        return new Complex(this.real+c.real, this.im+c.im);
    }
    
    public void subtract(Complex c)        //兩個對象相減
    {                                      //改變當前對象，沒有返回新對象
        this.real -= c.real;
        this.im -= c.im;
    }
    
    public Complex minus(Complex c)        //兩個對象相減，與subtract()方法參數一樣不能重載
    {                                      //返回新創建的對象，沒有改變當前對象
        return new Complex(this.real-c.real, this.im-c.im);
    }
}


class Complex__ex
{
    public static void main(String args[])
    {
        Complex a = new Complex(1,2);
        Complex b = new Complex(3,5);
        Complex c = a.plus(b);             //返回新創建對象
        System.out.println(a+" + "+b+" = "+c);
    } 
}

/*
程序運行結果如下：
(1.0+2.0i) + (3.0+5.0i) = (40.0+7.0i)

*/