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group:Value Types - Structures
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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.
hi
the struct gets allocated on the stack. What 'new ' does is initialize the value type's fields to null/zero regards Ansil [quoted text, click to view] "faktujaa" wrote:
> 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.
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 [quoted text, click to view] "Jon Skeet [C# MVP]" wrote:
> faktujaa <faktujaa@discussions.microsoft.com> wrote: > > Microsoft says that structures are value types. Also primitive data types > > are value types. And memory for value types is allocated on the stack. > > Memory for value types is only allocated on the stack in some cases. > See http://www.pobox.com/~skeet/csharp/memory.html > > > 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. > > "new" just means "call a constructor". It doesn't have anything to do > with where things are allocated. > > -- > Jon Skeet - <skeet@pobox.com> > http://www.pobox.com/~skeet > If replying to the group, please do not mail me too
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 [quoted text, click to view] "Jon Skeet [C# MVP]" wrote:
> Nishith Pathak <NishithPathak@discussions.microsoft.com> wrote: > > 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 > > The constructor probably actually sets member variables to *other* > values, actually. It's not much use as a constructor otherwise... > > -- > Jon Skeet - <skeet@pobox.com> > http://www.pobox.com/~skeet > If replying to the group, please do not mail me too
[quoted text, click to view]
faktujaa <faktujaa@discussions.microsoft.com> wrote: > Microsoft says that structures are value types. Also primitive data types > are value types. And memory for value types is allocated on the stack. Memory for value types is only allocated on the stack in some cases. See http://www.pobox.com/~skeet/csharp/memory.html [quoted text, click to view] > 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. "new" just means "call a constructor". It doesn't have anything to do with where things are allocated. -- Jon Skeet - <skeet@pobox.com> http://www.pobox.com/~skeet
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On Tue, 26 Oct 2004 08:11:03 -0700, faktujaa wrote: > 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 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_lunchmeat_[DOT]net To send me an E-mail, remove the "[", "]", underscores ,lunchmeat, and
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 [quoted text, click to view] "Chris Dunaway" <"dunawayc[[at]_lunchmeat" wrote:
> On Tue, 26 Oct 2004 08:11:03 -0700, faktujaa wrote: > > > 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 > > 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_lunchmeat_[DOT]net > > To send me an E-mail, remove the "[", "]", underscores ,lunchmeat, and > replace certain words in my E-Mail address.
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Nishith Pathak <NishithPathak@discussions.microsoft.com> wrote: > 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 The constructor probably actually sets member variables to *other* values, actually. It's not much use as a constructor otherwise... -- Jon Skeet - <skeet@pobox.com> http://www.pobox.com/~skeet
[quoted text, click to view]
faktujaa <faktujaa@discussions.microsoft.com> wrote: > 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. It just creates new instances, wherever they should go. It's as simple as that. -- Jon Skeet - <skeet@pobox.com> http://www.pobox.com/~skeet
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faktujaa <faktujaa@discussions.microsoft.com> wrote: > 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. 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.com> http://www.pobox.com/~skeet
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<Chris Dunaway <"dunawayc[[at]_lunchmeat_sbcglobal[dot]]net">> wrote: > > 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 > > Correct me if I'm wrong, but in C++, new is an operator whereas in VB New > is a method name. 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.com> http://www.pobox.com/~skeet
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 [quoted text, click to view] "Jon Skeet [C# MVP]" wrote:
> faktujaa <faktujaa@discussions.microsoft.com> wrote: > > 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. > > 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.com> > http://www.pobox.com/~skeet > If replying to the group, please do not mail me too
[quoted text, click to view]
Nishith Pathak <NishithPathak@discussions.microsoft.com> wrote: > 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 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.com> http://www.pobox.com/~skeet
Jon (& faktujaa),
[quoted text, click to view] > I'm not sure that it counts as an operator as such, but it's certainly VB.NET considers New an operator (when its not the identifier for the > a keyword rather than a method. 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 [quoted text, click to view] "Jon Skeet [C# MVP]" <skeet@pobox.com> wrote in message news:MPG.1be8bd82ecf4fbe898b809@msnews.microsoft.com... > <Chris Dunaway <"dunawayc[[at]_lunchmeat_sbcglobal[dot]]net">> wrote: >> > 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 >> >> Correct me if I'm wrong, but in C++, new is an operator whereas in VB New >> is a method name. > > 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.com> > http://www.pobox.com/~skeet > If replying to the group, please do not mail me too
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