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From: ThosRTanner on 29 Jan 2010 06:47
Why exactly is this allowed?

enum Fred { jim, bill, eric }

int main()
{
std::string x;
x = jim;
return 0;
}

eliding the constructor and the assignment elicits the expected error.
It hardly seems a useful thing to do.

It happens on 2 compilers

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From: Gert-Jan de Vos on 30 Jan 2010 03:13
On Jan 30, 12:47 am, ThosRTanner <ttann...(a)bloomberg.net> wrote:
> Why exactly is this allowed?
>
> enum Fred { jim, bill, eric }
>
> int main()
> {
> std::string x;
> x = jim;
> return 0;
>
> }

A char can be assigned to a string. enum constant to char is an
integral conversion. Your example assigns the value of jim (0)
as a character to the string x. This needs one implicit integral
conversion.


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From: Bo Persson on 30 Jan 2010 04:22
ThosRTanner wrote:
> Why exactly is this allowed?
>
> enum Fred { jim, bill, eric };
>
> int main()
> {
> std::string x;
> x = jim;
> return 0;
> }
>
> eliding the constructor and the assignment elicits the expected
> error. It hardly seems a useful thing to do.
>
> It happens on 2 compilers

It isn't exactly designed this way, but it just happens to work
according to the standard. :-(

The std::string class has an assignment operator for a single char,
allowing you to write

x = 'a';

Now, char is an integer type and enums are implicitly convertible to
integer types.

Blame it on C compatibility! :-)



Bo Persson



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