overloading operator >>

[wjyeo]

Hi i've have this problem in my code when i do the overloading of operator >>. My problem for this code isnt encounter error but my input like say i input 7, the num.a output will change this 7 to 55 and num.b output for 5 to 53. below is the code.

class Complex
{
	friend istream& operator>>(istream&, Complex&);
	friend ostream& operator<<(ostream&, const Complex&);
public:
	Complex(int a=0, int b=0) {};		// constructors
	Complex operator +(Complex);
	Complex operator *(Complex);
	bool operator ==(const Complex&) const;
	bool operator >(const Complex&) const;

private:
	int a, b;	
};

istream& operator>>(istream &in, Complex &num)
{
    string line="";
    fflush(stdin);
    in>>line;
    for(int i=0; i<line.length(); i++)
    {
            if(i==1)
            {
                 num.a = line[i];
            }
            else if(i==4)
            {
                 num.b = line[i];
            }     
    }         
	return in;
}

my format of input is (7+i3). This is a complex number format. Hope to hear the reply soon.Thanks

[Duoas]

Step by step.

1. Don't fflush(). There is no need and you shouldn't be mixing C and C++ I/O anyway.

2. You are mis-indexing the string: 01234 7+i3 Hence, line[1] == '+' and line[4] == '\0'. BTW, i never reaches 4 if your input is only four characters long.

3. You are not converting your numbers. The ASCII value of '+' is 43.

4. Your constructor should look like this: Complex( int _a=0, int _b=0 ): a( _a ), b( _b ) {}; or Complex( int _a=0, int _b=0 ) { a = _a; b = _b; } The first way is preferred.
The reason num.b is some weird number is because your constructor never initializes the private fields a and b. Having arguments with the same name makes no difference.

PS. Complex numbers are normally written a + bi. If you do the same you will have an easier time collecting and verifying input.

Hope this helps.

[wjyeo]

Thanks alot. actually my problem lies with the line thing, like you have explain. It turn out to be taken as ASCii '7' instead of int '7' thats y it output to 55. I actually did my changes by adding line - 48 to it to make it back to '7'. Really thanks alot abt the constructor thing.

[vijayan121]

> actually did my changes by adding line - 48 to it to make it back to '7'. line[i] - '0' would be much better; you program would then be not dependant on a particular character encoding.

[wjyeo]

Thanks alot for this '0' didnt realise can do it this way.