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C++ and OOPS Sample Question

11. class complex{
    	double re;
    	double im;
    public:
    	complex() : re(1),im(0.5) {}
    	bool operator==(complex &rhs);
    	operator int(){}
    };
    
    bool complex::operator == (complex &rhs){
    	if((this->re == rhs.re) && (this->im == rhs.im))
    		return true;
    	else
    		return false;
    }
    
    int main(){
    	complex  c1;
    	cout«  c1;
    }

    Answer :

    Garbage value

    Explanation :

    The programmer wishes to print the complex object using output re-direction operator,which he has not defined for his lass.But the compiler instead of giving an error sees the conversion function and converts the user defined object to standard object and prints some garbage value.

12. class complex{
    	double re;
    	double im;
    public:
    	complex() : re(0),im(0) {}
    	complex(double n) { re=n,im=n;};
    	complex(int m,int n) { re=m,im=n;}
    	void print() { cout«re; cout«im;}	
    };
    
    void main(){
    	complex c3;
    	double i=5;
    	c3 = i;
    	c3.print();
    }

    Answer :

    5,5

    Explanation :

    Though no operator= function taking complex, double is defined, the double on the rhs is converted into a temporary object using the single argument constructor taking double and assigned to the lvalue.

13. void main()
    {
    	int a, *pa, &ra;
    	pa = &a;
    	ra = a;
    	cout «"a="«a «"*pa="«*pa «"ra"«ra ;
    }

    Answer :

    Compiler Error: 'ra',reference must be initialized

    Explanation :

    Pointers are different from references. One of the main differences is that the pointers can be both initialized and assigned, whereas references can only be initialized. So this code issues an error.

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