Value Types - Structures

[faktujaa]

Hi All,
Microsoft says that structures are value types. Also primitive data types
are value types. And memory for value types is allocated on the stack. Then
why we need new operator to allocate memory for structure value types and not
for primitive data types(they r allocated memory on stack as well)??? Please
help.
Thanks in advance.
Faktujaa

[Ansil MCAD]

RE: Value Types - Structures

hi
the struct gets allocated on the stack.
What 'new ' does is initialize the value type's fields to null/zero

regards
Ansil

"faktujaa" wrote:
[color=blue]
> Hi All,
> Microsoft says that structures are value types. Also primitive data types
> are value types. And memory for value types is allocated on the stack. Then
> why we need new operator to allocate memory for structure value types and not
> for primitive data types(they r allocated memory on stack as well)??? Please
> help.
> Thanks in advance.
> Faktujaa[/color]

[Jon Skeet [C# MVP]]

Re: Value Types - Structures

faktujaa <faktujaa@discu ssions.microsof t.com> wrote:[color=blue]
> Microsoft says that structures are value types. Also primitive data types
> are value types. And memory for value types is allocated on the stack.[/color]

Memory for value types is only allocated on the stack in some cases.
See http://www.pobox.com/~skeet/csharp/memory.html
[color=blue]
> Then why we need new operator to allocate memory for structure value
> types and not for primitive data types(they r allocated memory on
> stack as well)??? Please help.[/color]

"new" just means "call a constructor". It doesn't have anything to do
with where things are allocated.

--
Jon Skeet - <skeet@pobox.co m>

http://www.pobox.com/~skeet

If replying to the group, please do not mail me too

[Nishith Pathak]

Re: Value Types - Structures

New has nothing to do with allocation of memory. It is used to call the
constructor.
so by using the new with a structure , you are calling a constructor of the
structure which sets all its members variables to 0, false or null depending
on their type

Nishith Pathak

"Jon Skeet [C# MVP]" wrote:
[color=blue]
> faktujaa <faktujaa@discu ssions.microsof t.com> wrote:[color=green]
> > Microsoft says that structures are value types. Also primitive data types
> > are value types. And memory for value types is allocated on the stack.[/color]
>
> Memory for value types is only allocated on the stack in some cases.
> See http://www.pobox.com/~skeet/csharp/memory.html
>[color=green]
> > Then why we need new operator to allocate memory for structure value
> > types and not for primitive data types(they r allocated memory on
> > stack as well)??? Please help.[/color]
>
> "new" just means "call a constructor". It doesn't have anything to do
> with where things are allocated.
>
> --
> Jon Skeet - <skeet@pobox.co m>
> http://www.pobox.com/~skeet
> If replying to the group, please do not mail me too
>[/color]

[Jon Skeet [C# MVP]]

Re: Value Types - Structures

Nishith Pathak <NishithPathak@ discussions.mic rosoft.com> wrote:[color=blue]
> New has nothing to do with allocation of memory. It is used to call the
> constructor.
> so by using the new with a structure , you are calling a constructor of the
> structure which sets all its members variables to 0, false or null depending
> on their type[/color]

The constructor probably actually sets member variables to *other*
values, actually. It's not much use as a constructor otherwise...

--
Jon Skeet - <skeet@pobox.co m>

http://www.pobox.com/~skeet

If replying to the group, please do not mail me too

[faktujaa]

Re: Value Types - Structures

Thanks for the inputs. Then how does CLR knows that it has to allocate the
memory on stack/heap. By this, i think it determines based on the type
name(class). Actually i was thinking that by creating a variable with new
keyword, we assign the memory on the heap as in C/C++. Anyways thanks for the
help but still the question of how does the CLR knows abt where to allocate
the memory is bothering me. Please help.
Faktujaa

"Jon Skeet [C# MVP]" wrote:
[color=blue]
> Nishith Pathak <NishithPathak@ discussions.mic rosoft.com> wrote:[color=green]
> > New has nothing to do with allocation of memory. It is used to call the
> > constructor.
> > so by using the new with a structure , you are calling a constructor of the
> > structure which sets all its members variables to 0, false or null depending
> > on their type[/color]
>
> The constructor probably actually sets member variables to *other*
> values, actually. It's not much use as a constructor otherwise...
>
> --
> Jon Skeet - <skeet@pobox.co m>
> http://www.pobox.com/~skeet
> If replying to the group, please do not mail me too
>[/color]

[Chris Dunaway]

Re: Value Types - Structures

On Tue, 26 Oct 2004 08:11:03 -0700, faktujaa wrote:
[color=blue]
> name(class). Actually i was thinking that by creating a variable with new
> keyword, we assign the memory on the heap as in C/C++. Anyways thanks for the[/color]

Correct me if I'm wrong, but in C++, new is an operator whereas in VB New
is a method name.

--
Chris

dunawayc[AT]sbcglobal_lunch meat_[DOT]net

To send me an E-mail, remove the "[", "]", underscores ,lunchmeat, and
replace certain words in my E-Mail address.

[faktujaa]

Re: Value Types - Structures

Hi,
Im was not talking of C++ and VB but of C#/VB.NET and C++/VB. Anyways im not
a VB guy so i don't know anything abt it. Also as per microsoft, the new
keyword can be used as an operator or as a modifier in C#. As an operator, is
used to create objects on the heap and invoke constructors. Then by using the
same new operator to create an object of structure type, why do it allocates
the memory on the stack. Any help on this is highly appreciated. Thanks in
advance.
faktujaa

"Chris Dunaway" <"dunawayc[[at]_lunchmeat" wrote:
[color=blue]
> On Tue, 26 Oct 2004 08:11:03 -0700, faktujaa wrote:
>[color=green]
> > name(class). Actually i was thinking that by creating a variable with new
> > keyword, we assign the memory on the heap as in C/C++. Anyways thanks for the[/color]
>
> Correct me if I'm wrong, but in C++, new is an operator whereas in VB New
> is a method name.
>
> --
> Chris
>
> dunawayc[AT]sbcglobal_lunch meat_[DOT]net
>
> To send me an E-mail, remove the "[", "]", underscores ,lunchmeat, and
> replace certain words in my E-Mail address.
>[/color]

[Jon Skeet [C# MVP]]

Re: Value Types - Structures

faktujaa <faktujaa@discu ssions.microsof t.com> wrote:[color=blue]
> Im was not talking of C++ and VB but of C#/VB.NET and C++/VB. Anyways im not
> a VB guy so i don't know anything abt it. Also as per microsoft, the new
> keyword can be used as an operator or as a modifier in C#. As an operator, is
> used to create objects on the heap and invoke constructors. Then by using the
> same new operator to create an object of structure type, why do it allocates
> the memory on the stack. Any help on this is highly appreciated. Thanks in
> advance.[/color]

It just creates new instances, wherever they should go. It's as simple
as that.

--
Jon Skeet - <skeet@pobox.co m>

http://www.pobox.com/~skeet

If replying to the group, please do not mail me too

[Jon Skeet [C# MVP]]

Re: Value Types - Structures

faktujaa <faktujaa@discu ssions.microsof t.com> wrote:[color=blue]
> Thanks for the inputs. Then how does CLR knows that it has to allocate the
> memory on stack/heap. By this, i think it determines based on the type
> name(class). Actually i was thinking that by creating a variable with new
> keyword, we assign the memory on the heap as in C/C++. Anyways thanks for the
> help but still the question of how does the CLR knows abt where to allocate
> the memory is bothering me. Please help.[/color]

Did you read the article I linked to? It explains it all there.

http://www.pobox.com/~skeet/csharp/memory.html

--
Jon Skeet - <skeet@pobox.co m>

http://www.pobox.com/~skeet

If replying to the group, please do not mail me too

[Jon Skeet [C# MVP]]

Re: Value Types - Structures

<Chris Dunaway <"dunawayc[[at]_lunchmeat_sbcg lobal[dot]]net">> wrote:[color=blue][color=green]
> > name(class). Actually i was thinking that by creating a variable with new
> > keyword, we assign the memory on the heap as in C/C++. Anyways thanks for the[/color]
>
> Correct me if I'm wrong, but in C++, new is an operator whereas in VB New
> is a method name.[/color]

I'm not sure that it counts as an operator as such, but it's certainly
a keyword rather than a method.

--
Jon Skeet - <skeet@pobox.co m>

http://www.pobox.com/~skeet

If replying to the group, please do not mail me too

[Nishith Pathak]

Re: Value Types - Structures

CLR determin the allocation on heap or stack by checking its type. For
example if it is int since it is been a System,int32 structure so it is
always be allocated on stack and if it string which represent. System.String
class then it is allocated on the Heap.CLR does not look for the new keyword
to allocate it in Heap or stack. New keyword is just to initialise the memory
through the use of constructor

Hope it helps you

Nishith

"Jon Skeet [C# MVP]" wrote:
[color=blue]
> faktujaa <faktujaa@discu ssions.microsof t.com> wrote:[color=green]
> > Thanks for the inputs. Then how does CLR knows that it has to allocate the
> > memory on stack/heap. By this, i think it determines based on the type
> > name(class). Actually i was thinking that by creating a variable with new
> > keyword, we assign the memory on the heap as in C/C++. Anyways thanks for the
> > help but still the question of how does the CLR knows abt where to allocate
> > the memory is bothering me. Please help.[/color]
>
> Did you read the article I linked to? It explains it all there.
>
> http://www.pobox.com/~skeet/csharp/memory.html
>
> --
> Jon Skeet - <skeet@pobox.co m>
> http://www.pobox.com/~skeet
> If replying to the group, please do not mail me too
>[/color]

[Jon Skeet [C# MVP]]

Re: Value Types - Structures

Nishith Pathak <NishithPathak@ discussions.mic rosoft.com> wrote:[color=blue]
> CLR determin the allocation on heap or stack by checking its type. For
> example if it is int since it is been a System,int32 structure so it is
> always be allocated on stack[/color]

No it won't. For instance:

class Test
{
int i;
}

The integer here is part of a class, and will always be on the heap,
despite being a value type. Claiming that value types are always
allocated on the stack is misleading and incorrect.

Please see the article I linked to previously.

--
Jon Skeet - <skeet@pobox.co m>

http://www.pobox.com/~skeet

If replying to the group, please do not mail me too

[Jay B. Harlow [MVP - Outlook]]

Re: Value Types - Structures

Jon (& faktujaa),[color=blue]
> I'm not sure that it counts as an operator as such, but it's certainly
> a keyword rather than a method.[/color]
VB.NET considers New an operator (when its not the identifier for the
constructor, aka a method name):

http://msdn.microsoft.com/library/default.asp?url=/library/en-us/vbls7/html/vblrfVBSpec9_6.asp

C# considers new an operator (when its not a modifier):

http://msdn.microsoft.com/library/default.asp?url=/library/en-us/csref/html/vclrfNewOpPG.asp

In both case the New operator creates an "object" & calls a constructor. As
you know in the case of a value type the "object" is created "inline" (stack
or another object), while for reference types the "object" is created on the
heap.

I've always considered new an operator in C++ also, as the new operator (in
C++) also allocates space for the object & calls the constructor.

Hope this helps
Jay

"Jon Skeet [C# MVP]" <skeet@pobox.co m> wrote in message
news:MPG.1be8bd 82ecf4fbe898b80 9@msnews.micros oft.com...[color=blue]
> <Chris Dunaway <"dunawayc[[at]_lunchmeat_sbcg lobal[dot]]net">> wrote:[color=green][color=darkred]
>> > name(class). Actually i was thinking that by creating a variable with
>> > new
>> > keyword, we assign the memory on the heap as in C/C++. Anyways thanks
>> > for the[/color]
>>
>> Correct me if I'm wrong, but in C++, new is an operator whereas in VB New
>> is a method name.[/color]
>
> I'm not sure that it counts as an operator as such, but it's certainly
> a keyword rather than a method.
>
> --
> Jon Skeet - <skeet@pobox.co m>
> http://www.pobox.com/~skeet
> If replying to the group, please do not mail me too[/color]