operator overloading

This is a discussion on operator overloading within the C++ Programming forums, part of the General Programming Boards category; I overloaded << operator to format output in this fashion "(" variable1 ", " variable2 ", " variable3 ")"; Lets ...

  1. #1
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    operator overloading

    I overloaded << operator to format output in this fashion
    "(" variable1 ", " variable2 ", " variable3 ")";
    Lets say that my Vector class has another methods and I want to output those methods in normal way. How to undone overloading operator <<? What to write and where in the code?
    Code:
    #include <d3dx10.h>
    #include <iostream>
    using namespace std;
    
    // Overload the  "<<" operators so that we can use cout to 
    // output D3DXVECTOR3 objects.
    
    ostream& operator<<(ostream& os, D3DXVECTOR3& v)
    {
    	os << "(" << v.x << ", " << v.y << ", " << v.z << ")";
    	return os;
    }
    
    int main()
    {
    	// Using constructor, D3DXVECTOR3(FLOAT x, FLOAT y, FLOAT z);
    	D3DXVECTOR3 u(1.0f, 2.0f, 3.0f);
    
    	// Using constructor, D3DXVECTOR3(CONST FLOAT *);
    	float x[3] = {-2.0f, 1.0f, -3.0f};
    	D3DXVECTOR3 v(x);
    
    	// Using constructor, D3DXVECTOR3() {};
    	D3DXVECTOR3 a, b, c, d, e;  
    
    	// Vector addition: D3DXVECTOR3 operator + 
    	a = u + v;
    
    	// Vector subtraction: D3DXVECTOR3 operator - 
    	b = u - v;
    
    	// Scalar multiplication: D3DXVECTOR3 operator * 
    	c = u * 10;
    
    	// ||u||
    	float L = D3DXVec3Length(&u);
    
    	// d = u / ||u||
    	D3DXVec3Normalize(&d, &u);
    
    	// s = u dot v
    	float s = D3DXVec3Dot(&u, &v);
    
    	// e = u x v
    	D3DXVec3Cross(&e, &u, &v);
    
    	cout << "u             = " << u << endl;
    	cout << "v             = " << v << endl;
    	cout << "a = u + v     = " << a << endl;
    	cout << "b = u - v     = " << b << endl;
    	cout << "c = u * 10    = " << c << endl;
    	cout << "d = u / ||u|| = " << d << endl;
    	cout << "e = u x v     = " << e << endl;
    	cout << "L = ||u||     = " << L << endl;
    	cout << "s = u.v       = " << s << endl;
    
    	return 0;
    }

  2. #2
    C++ Witch laserlight's Avatar
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    I do not really understand your question, but it sounds like you should just write another function to print in the exact way that you want.
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  3. #3
    Registered User hk_mp5kpdw's Avatar
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    Quote Originally Posted by dontoo View Post
    I overloaded << operator to format output in this fashion
    "(" variable1 ", " variable2 ", " variable3 ")";
    Lets say that my Vector class has another methods and I want to output those methods in normal way. How to undone overloading operator <<? What to write and where in the code?
    How do you output a method? Do you mean produce output from within a method? What's the normal way? Either you handle the output in a different way within those methods on an individual basis or you can do something that I've done using a static data member and member function that sets and stores the current output type so that the print routine can do something different depending on what the value is:
    Code:
    #include <iostream>
    
    class foo
    {
    public:
        enum out_type {TYPE1,TYPE2,TYPE3};
        int data;
        foo(int _data = 0) : data(_data)
        {
        }
        std::ostream& print(std::ostream& os) const
        {
            if(output == TYPE1)
                return os << "This is format 1: " << data;
            else if(output==TYPE2)
                return os << "This is format 2: \"" << data << '\"';
            else if(output==TYPE3)
                return os << "This is format 3: ***" << data << "***";
            else return os;
        }
        static void SetOutputType(out_type typ)
        {
            output = typ;
        }
    private:
        static out_type output;
    };
    
    foo::out_type foo::output;
    
    std::ostream& operator<<(std::ostream& os, const foo& rhs)
    {
        return rhs.print(os);
    }
    
    int main()
    {
        foo bar1, bar2(10);
    
        foo::SetOutputType(foo::TYPE1);
        std::cout << bar1 << '\n' << bar2 << '\n' << std::endl;
    
        foo::SetOutputType(foo::TYPE2);
        std::cout << bar1 << '\n' << bar2 << '\n' << std::endl;
    
        foo::SetOutputType(foo::TYPE3);
        std::cout << bar1 << '\n' << bar2 << '\n' << std::endl;
    
        return 0;
    }
    Output is as follows:
    Code:
    This is format 1: 0
    This is format 1: 10
    
    This is format 2: "0"
    This is format 2: "10"
    
    This is format 3: ***0***
    This is format 3: ***10***
    "Owners of dogs will have noticed that, if you provide them with food and water and shelter and affection, they will think you are god. Whereas owners of cats are compelled to realize that, if you provide them with food and water and shelter and affection, they draw the conclusion that they are gods."
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  4. #4
    Registered User
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    Feb 2010
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    7
    That will work, thx

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