Re: overloading for multiple arithmetic operations

Pete Becker <>
Tue, 13 Jul 2010 20:48:20 CST
On 2010-07-13 12:43:44 -0400, Dominic Chandar said:


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


using namespace std;
 class Test
     Test(float _code){ code = _code;}
     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 ?

Presumably "fail" here means "doesn't compile and produces error
messages that haven't been included in this message". Error messages
are your friend! Read them!

Off hand, it looks like ob1 + ob2 is returning a Test object, and since
operator+ takes a non-const Test object, it can't be called with a
temporary. Both free functions should take their Test object by const
reference or by value, and the member operator+ should be marked const.

Roundhouse Consulting, Ltd. ( Author of "The
Standard C++ Library Extensions: a Tutorial and Reference

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