Andrew Haley <aph@xxxxxxxxxx> writes:
> On 11/12/2010 03:21 PM, Francis Moreau wrote:
>> Andrew Haley <aph@xxxxxxxxxx> writes:
>>
>>> On 11/12/2010 02:55 PM, Francis Moreau wrote:
>
>>>> "Segher Boessenkool" <segher@xxxxxxxxxxxxxxxxxxx> writes:
>>>>
>>>> [...]
>>>
>>>>
>>>>>>
>>>>>> Looking again at the second example:
>>>>>>
>>>>>> int f() {
>>>>>> union a_union t;
>>>>>> int* ip;
>>>>>> t.d = 3.0;
>>>>>> ip = &t.i;
>>>>>> return *ip;
>>>>>> }
>>>>>>
>>>>>> could you tell me what the effective type of 't.i' object ?
>>>>>
>>>>> int, if you can say that object exists at all: it does not have a stored
>>>>> value. The stored value of t is a double with value 3.0 . You can
>>>>> take its address and access it via that as "double" (or "char"), or you
>>>>> can access it as the union it is. You can not access it as "int".
>>>>>
>>>>
>>>> BTW, does your reasoning rely on the C standard ?
>>>
>>> It's a gcc extension. 5.25, Cast to a Union Type
>>
>> How can it be related with the existence of an union member ?
>
> I don't understand your question. Rather than attempt to answer,
> I'll ask you to rephrase your question.
Please see my answer to Segher.
--
Francis
