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Groups > comp.lang.c > #150258
| Newsgroups | comp.lang.c |
|---|---|
| Date | 2020-02-25 19:19 -0800 |
| References | <aaf0f57f-4ae1-4c4a-a0aa-314eade48440@googlegroups.com> |
| Message-ID | <3c3d49d5-e488-4c36-b73b-87de4eb9d032@googlegroups.com> (permalink) |
| Subject | Re: clarification about enums in C |
| From | luser droog <luser.droog@gmail.com> |
On Tuesday, February 25, 2020 at 5:38:47 PM UTC-6, Thiago Adams wrote:
> From the standard:
>
> "The identifiers in an enumerator list are declared as constants
> that have type int and may appear wherever such are permitted.127)"
>
> But there is a foot note:
>
> "Each enumerated type shall be compatible with char, a signed
> integer type, or an unsigned integer type. The choice of type
> is implementation-defined,128)"
>
> "128) An implementation may delay the choice of which integer
> type until all enumeration constants have been seen."
>
> I am confused.
>
> enum E { A, B};
>
> Can A and B be int and E not int?
> Can A B and E be != int?
>
> If so, what is this
>
> "The identifiers in an enumerator list are declared as constants
> that have type int and may appear wherever such are permitted.127)"
It's talking about declaring a enum variable.
enum E myenum;
What type is 'myenum'? It might seem obvious to implement as the
same as an int. But in the your example, having only two names A and B,
that could comfortable fit in a signed char. So the compiler is
given leeway to choose the *underlying* type. The names A and B yield
int in an expression, but in most expressions the promotion rules
would probably convert it to int anyway, ie. even if it were to yield a
signed char sometimes.
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clarification about enums in C Thiago Adams <thiago.adams@gmail.com> - 2020-02-25 15:38 -0800
Re: clarification about enums in C luser droog <luser.droog@gmail.com> - 2020-02-25 19:19 -0800
Re: clarification about enums in C James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-02-25 21:17 -0800
Re: clarification about enums in C Thiago Adams <thiago.adams@gmail.com> - 2020-02-27 04:01 -0800
Re: clarification about enums in C David Brown <david.brown@hesbynett.no> - 2020-02-26 11:29 +0100
Re: clarification about enums in C already5chosen@yahoo.com - 2020-02-26 14:05 -0800
Re: clarification about enums in C Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-02-26 23:03 +0000
Re: clarification about enums in C already5chosen@yahoo.com - 2020-02-26 23:29 -0800
Re: clarification about enums in C already5chosen@yahoo.com - 2020-02-27 01:42 -0800
Re: clarification about enums in C David Brown <david.brown@hesbynett.no> - 2020-02-27 11:02 +0100
Re: clarification about enums in C Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-02-27 06:37 -0800
Re: clarification about enums in C David Brown <david.brown@hesbynett.no> - 2020-02-27 16:18 +0100
Re: clarification about enums in C James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-02-27 23:24 -0500
Re: clarification about enums in C David Brown <david.brown@hesbynett.no> - 2020-02-27 09:50 +0100
Re: clarification about enums in C Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-02-27 06:33 -0800
Re: clarification about enums in C already5chosen@yahoo.com - 2020-02-27 06:53 -0800
Re: clarification about enums in C Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-02-27 15:05 +0000
Re: clarification about enums in C David Brown <david.brown@hesbynett.no> - 2020-02-27 16:24 +0100
Re: clarification about enums in C Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-02-28 01:27 -0800
Re: clarification about enums in C already5chosen@yahoo.com - 2020-02-27 01:29 -0800
Re: clarification about enums in C David Brown <david.brown@hesbynett.no> - 2020-02-27 11:12 +0100
Re: clarification about enums in C already5chosen@yahoo.com - 2020-02-27 03:09 -0800
Re: clarification about enums in C David Brown <david.brown@hesbynett.no> - 2020-02-27 14:33 +0100
Re: clarification about enums in C already5chosen@yahoo.com - 2020-02-27 05:44 -0800
Re: clarification about enums in C David Brown <david.brown@hesbynett.no> - 2020-02-27 14:57 +0100
Re: clarification about enums in C Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-02-27 11:53 +0000
Re: clarification about enums in C James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-02-27 23:52 -0500
Re: clarification about enums in C Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-02-28 01:30 -0800
Re: clarification about enums in C Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-02-26 14:09 +0000
Re: clarification about enums in C Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-02-26 09:47 -0800
Re: clarification about enums in C Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-02-26 21:04 +0000
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