overloading for multiple arithmetic operations

Hi,

    I would like to add multiple objects of a class with integers/
floats. Need some basic help in fixing an error

Eg:

 #include<iostream>
using namespace std;
 class Test
 {
     public:
     Test(float _code){ code = _code;}
     Test(){}
     float code;
     friend Test operator+(Test & ob, float val);
     friend Test operator+(float val, Test & ob);
     Test operator+(Test & ob);
 };
Test Test::operator+(Test & ob)
{
  Test temp;
  temp.code = this->code + ob.code;
  return temp;
}
Test operator+(Test & ob, float val)
{
   Test temp;
   temp.code = ob.code + val;
   return temp;
 }
Test operator+(float val, Test & ob)
{
   Test temp;
   temp.code = ob.code + val;
   return temp;
}
int main()
{
  Test ob1(1.0), ob2(2.0), ob3(3.0), ob4(0.0);
  float c1=100.5 ;

   ob4 = ob1+ob2+ob3 ; // This works
   ob4 = ob1+c1; // This works
   ob4 = ob1 + ob2 + c1 ;// Does not work... why ?
   ob4 = ob1 + c1 + ob2 ;// This works...

  return 0;
}

My question is : why does the third operation ob4 = ob1 + ob2 + c1
fail ?

-Dominic

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