unary operator overloading c++

Question

I'm having trouble with the unary ++ overloaded operator.

Here is my code...

 #include<iostream>

 using namespace std;

 class Index{

      int value;
 public:
     Index() : value(0) { }
     int GetIndex() const
     {
        return value;
     }
     void operator ++()
     {
        value++;
     }
};
int main()
{   
   Index idx1,idx2;

   ++idx1;
   idx2++;
   idx2++;

   cout << "idx1.value:" << idx1.GetIndex() << endl;
   cout << "idx2.value:" << idx2.GetIndex() << endl;


 }

The statement idx2++ is giving me a compilation error.The prefix however i.e ++idx1 is working properly.The book I'm referring to says that both should give the same output...i.e the value member must get incremented by 1.

Why am I facing this problem??...The IDE I'm using is visual studio 2015.

The [example here](https://msdn.microsoft.com/en-us/library/f6s9k9ta.aspx) might help — Ed Heal, Jun 20 '16 at 19:08

score 2 · Answer 1 · answered Jun 20 '16 at 19:08

2

Prefix and postfix ++ are two separate operators. C++ differentiates them by taking a dummy int param for postfix and no param for prefix.

answered Jun 20 '16 at 19:08

lorro

10,687
23
36

Thanks...I got it now – user5422891 Jun 21 '16 at 06:27

score 1 · Answer 2 · answered Jun 20 '16 at 19:08

1

https://en.wikipedia.org/wiki/Operators_in_C_and_C%2B%2B

The signature for the postfix-increment operator overload is TYPE operator ++(int)

answered Jun 20 '16 at 19:08

tkausl

13,686
2
33
50

Thanks for the link... – user5422891 Jun 21 '16 at 06:31

unary operator overloading c++

2 Answers2