Hi Saurabh
Thanks for the document. Please refer to start of page 214, Section 8.5.4
,point 3, Below is example from that
struct S2 {
int m1;
double m2, m3;
};
S2 s21 = { 1, 2, 3.0 }; // OK
S2 s22 { 1.0, 2, 3 }; error: narrowing
S2 s23 { }; // OK: default to 0,0,0
I tried the above case with valgrind, even valgrind had not shown any
un-initialized read.
Document also says it is incomplete and incorrect.
Thanks
Sagar
On Sun, Sep 28, 2014 at 4:41 PM, saurabh singh <[email protected]> wrote:
> Here you go
> http://www.open-std.org/JTC1/SC22/WG21/docs/papers/2012/n3337.pdf
> The c++ standard itself. Refer to section 8.5.4 page no. 213.
> Looks like even this int a[10] = {2} is not guaranteed to initialize all
> the elements of the array. Sure gcc provides this but then it becomes a
> compiler specific thing. The language doesn't advocates it.
>
> Saurabh Singh
> B.Tech (Computer Science)
> MNNIT
> blog:geekinessthecoolway.blogspot.com
>
> On Sun, Sep 28, 2014 at 3:47 PM, sagar sindwani <[email protected]>
> wrote:
>
>> Thanks Deepak and Rahul for the reply.
>>
>> Do you guys have any standard document or any standard book which defines
>> this? I totally agree with these answers but I don't have any formal
>> written text.
>>
>> In my example 1, the object is on stack and this lead to a1[0].z to be
>> un-initialized. But as the specified in example 2, Why every element of arr
>> is initialized, it is also on the stack ? Any source to answer this
>> question ?
>>
>> Thanks
>> Sagar
>>
>>
>>
>> On Sun, Sep 28, 2014 at 2:26 PM, Rahul Vatsa <[email protected]>
>> wrote:
>>
>>>
>>> http://stackoverflow.com/questions/3127454/how-do-c-class-members-get-initialized-if-i-dont-do-it-explicitly
>>>
>>> On Sun, Sep 28, 2014 at 12:22 PM, Deepak Garg <[email protected]>
>>> wrote:
>>>
>>>> Hi
>>>>
>>>> In example 1, member z will have a garbage value (i.e. 0 in your case )
>>>>
>>>> Thanks
>>>> Deepak
>>>> On Sep 28, 2014 11:29 AM, "sagar sindwani" <[email protected]>
>>>> wrote:
>>>>
>>>>> I am working on How compilers handle initialization list. I came
>>>>> across a case where I am not sure what should be the compiler behaviour.
>>>>>
>>>>> *Example 1:-*
>>>>>
>>>>> #include <iostream>
>>>>>
>>>>> class A
>>>>> {
>>>>> public:
>>>>> int x,y,z;
>>>>> };
>>>>>
>>>>> int main()
>>>>> {
>>>>> A a1[2] =
>>>>> {
>>>>> { 1,2 },
>>>>> { 3,4 }
>>>>> };
>>>>>
>>>>> std::cout << "a1[0].z is " << a1[0].z << std::endl;
>>>>>
>>>>> return 0;
>>>>> }
>>>>>
>>>>> In above case a1[0].z is ? g++ shows it as 0 ( zero ). It is exactly 0
>>>>> or garbage value, I am not sure on that.
>>>>>
>>>>> I tried lot of books and some documents , no where I found what C++
>>>>> says for initialization of class objects.
>>>>>
>>>>> You can find handling of below case in almost every book.
>>>>>
>>>>> *Example 2:- *
>>>>>
>>>>> int arr[6] = {0};
>>>>>
>>>>> In Example 2, compilers will auto-fill all members with 0. It is
>>>>> mentioned in books. But when it comes to User-defined datatypes nothing is
>>>>> mentioned.
>>>>>
>>>>>
>>>>> Please share your thoughts on this. If you find any document related
>>>>> to this, please share it as well.
>>>>>
>>>>> Thanks
>>>>> Sagar
>>>>>
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