subject:"Re\: \[algogeeks\] C\+\+ initialization list"

Re: [algogeeks] C++ initialization list

2014-09-28 Thread Deepak Garg

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 sindwani.sa...@gmail.com 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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Re: [algogeeks] C++ initialization list

2014-09-28 Thread Rahul Vatsa

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 deepakgarg...@gmail.com
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 sindwani.sa...@gmail.com
 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

 --
 You received this message because you are subscribed to the Google Groups
 Algorithm Geeks group.
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Re: [algogeeks] C++ initialization list

2014-09-28 Thread sagar sindwani

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 vatsa.ra...@gmail.com 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 deepakgarg...@gmail.com
 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 sindwani.sa...@gmail.com
 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

 --
 You received this message because you are subscribed to the Google
 Groups Algorithm Geeks group.
 To unsubscribe from this group and stop receiving emails from it, send
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Re: [algogeeks] C++ initialization list

2014-09-28 Thread Deepak Garg

Hi sagar

Actually its the compiler which is doing things for you.
GCC or G++ have some features that allows you to initialize array. For
example in your case 2 when you specify a single element gcc intializes the
whole array with 0. You can do this also:
Int arr [6]={[3]=0, [4]=5} p.s. gcc allows u to do this type of
initialisation.
You can refer gcc doc online for more info.
On Sep 28, 2014 3:59 PM, sagar sindwani sindwani.sa...@gmail.com 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 vatsa.ra...@gmail.com
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 deepakgarg...@gmail.com
wrote:

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 sindwani.sa...@gmail.com
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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You received this message because you are subscribed to the Google
Groups Algorithm Geeks group.
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Re: [algogeeks] C++ initialization list

2014-09-28 Thread saurabh singh

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 sindwani.sa...@gmail.com
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.

Thanks
Sagar

On Sun, Sep 28, 2014 at 2:26 PM, Rahul Vatsa vatsa.ra...@gmail.com
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 deepakgarg...@gmail.com
wrote:

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 sindwani.sa...@gmail.com
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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Re: [algogeeks] C++ initialization list

2014-09-28 Thread sagar sindwani

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 saurab...@gmail.com wrote:

Saurabh Singh
B.Tech (Computer Science)
MNNIT
blog:geekinessthecoolway.blogspot.com

On Sun, Sep 28, 2014 at 3:47 PM, sagar sindwani sindwani.sa...@gmail.com
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.

Thanks
Sagar

On Sun, Sep 28, 2014 at 2:26 PM, Rahul Vatsa vatsa.ra...@gmail.com
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 deepakgarg...@gmail.com
wrote:

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 sindwani.sa...@gmail.com
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

--
You received this message because you are subscribed to the Google Groups
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email to algogeeks+unsubscr...@googlegroups.com.

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Re: [algogeeks] C++ initialization list

Re: [algogeeks] C++ initialization list

Re: [algogeeks] C++ initialization list

Re: [algogeeks] C++ initialization list

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Re: [algogeeks] C++ initialization list

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