关于C++转换构造函数的问题求教！

//本人用的是VS2010，编写了这个程序实现运算符的重载，中间用到了转换构造函数，但是程序一直编译不通过，请问是我的代码问题还是VS2010的问题吗？
#include<iostream>
using namespace std;
class Complex
{
public:
    Complex();
    Complex(int,int);
    ~Complex();
    Complex(double r){real=r;imag=0;}                   //此处定义转换构造函数
    friend Complex operator+(Complex &a,Complex &b);
    friend Complex operator-(Complex &a,Complex &b);
    friend Complex operator*(Complex &a,Complex &b);
    friend Complex operator/(Complex &a,Complex &b);
    friend ostream&operator<<(ostream&output,Complex&exp);
    friend istream&operator>>(istream&input,Complex&exp);
private:
    double real;
    double imag;
};

Complex::Complex(){}
Complex::Complex(int a,int b):real(a),imag(b){}
Complex::~Complex(){}

Complex operator+(Complex &a,Complex &b)
{
    return Complex(a.real+b.real,a.imag+b.imag);
}

Complex operator-(Complex &a,Complex &b)
{
    return Complex(a.real-b.real,a.imag-b.imag);
}

Complex operator*(Complex &a,Complex &b)
{
    return Complex((a.real*b.real-a.imag*b.imag),(a.real*b.imag+a.imag*b.real));
}

Complex operator/(Complex &a,Complex &b)
{
    return Complex((a.real*b.real+a.imag*b.imag)/(b.real*b.real+b.imag*b.imag),(a.imag*b.real-a.real*b.imag)/(b.real*b.real+b.imag*b.imag));
}

ostream&operator<<(ostream&output,Complex&exp)
{
    if(exp.imag<0)
        output<<exp.real<<"+"<<-exp.imag<<"i";
    else
        output<<exp.real<<"+"<<exp.imag<<"i";
    return output;
}

istream&operator>>(istream&input,Complex&exp)
{
    input>>exp.real>>exp.imag;
    return input;
}

int main()
{
    Complex a,b,c;
    double d=9;
    cin>>a;
    c=a+d;      //此处想利用转换构造函数将d转换为Complex类型（9+0i）然后利用运算符重载进行计算，但一直出错！
    cout<<c<<endl;
    system("pause");

}