expected initializer before '&' token in enumarator operator overloading C++

Question

I want to write overloading operator, that increments enum type:

#include <iostream>
#include <vector>
#include <string>
#include <stdexcept>
using namespace std;


enum Type {grun,grun_blinkend,gelb,rot ,rot_gelb,gelb_blinkend}



Type& operator++(Type& color){
    return color = static_cast<Type>(++static_cast<int>(Type)); 
};

But it throws me an error:

error: expected initializer before '&' token

Why and how can I fix it?

I need this operator in order to iterate over the Type for "traffic light" simulation:

Ampel Ampel::weiter(){
    if(zustand ==  Type(rot_gelb)){
        zustand = Type(grun);
        return Ampel(zustand);
    }
    ++zustand;
    return Ampel(zustand);
}

Perhaps it might also be useful to explain the rationale behind this operator? There might be a whole different solution to your actual problem. — Maarten Bamelis, Dec 08 '17 at 12:13
You forgot a semicolon after the enum definition. Voting to close as typo. — molbdnilo, Dec 08 '17 at 12:19
What if the value of `color` is `gelb_blinkend`? What happens then when you "increase" it? What will `color` then be? — Some programmer dude, Dec 08 '17 at 12:20
@molbdnilo What about some of the other errors? The increment requires an lvalue and the argument of the cast is a type and not an identifier. — Maarten Bamelis, Dec 08 '17 at 12:25
@MaartenBamelis Those are unrelated to the error message in question. — molbdnilo, Dec 08 '17 at 12:28
To clarify: without the semicolon, the compiler sees `enum Type { ... } Type ...` and expects the variable `Type` (which has the type `Type`) to have an initializer. — molbdnilo, Dec 08 '17 at 12:33

score 1 · Accepted Answer · answered Dec 08 '17 at 12:28

This is a solution, but you must be cautious about an integer higher to gelb_blinkend, for a good explanation about that I recommend see this question and also you should think about change enum for enum class, for this I suggest this another question.

enum Type {grun,grun_blinkend,gelb,rot ,rot_gelb,gelb_blinkend};

Type& operator++(Type& color){
    int current = static_cast<int>(color);
    return color = static_cast<Type>(++current); 
};

expected initializer before '&' token in enumarator operator overloading C++

1 Answers1