design question : struct or class

[phoenix]

Hello,

I've got a design question. I need to keep track of some variables and I am
planning to put them inside a class or struct. Basically I'm talking about
10 bools, 20 ints and 2 arrays of ints. The size of the arrays would depend
on some external value (going from 0 to around 1000 max). I would have an
array of max 255 of these classes/structs (in most cases it will be less
then 5 however)

Since there's no real business logic my choice would be structs. But looking
at the size of the objects in memory I would think they are a bit large to
put on the stack and should be better of on the heap. Which would mean I
should use classes.

Any ideas about what would be best?

TIA

Yves

[Jay B. Harlow [MVP - Outlook]]

Re: design question : struct or class

Phoenix,[color=blue]
> Since there's no real business logic my choice would be structs.[/color]
Structs can have "business logic" as equally well as classes.

I normally make every thing a class, unless I know I need a struct, I use
the following to know I need a struct:
- act like a primitive type
- have an instance size under 16 bytes
- are immutable
- value semantics are desirable

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

Hope this helps
Jay

"phoenix" <patient0@skyne tWORK.be> wrote in message
news:O1efil54DH A.1948@TK2MSFTN GP12.phx.gbl...[color=blue]
> Hello,
>
> I've got a design question. I need to keep track of some variables and I[/color]
am[color=blue]
> planning to put them inside a class or struct. Basically I'm talking about
> 10 bools, 20 ints and 2 arrays of ints. The size of the arrays would[/color]
depend[color=blue]
> on some external value (going from 0 to around 1000 max). I would have an
> array of max 255 of these classes/structs (in most cases it will be less
> then 5 however)
>
> Since there's no real business logic my choice would be structs. But[/color]
looking[color=blue]
> at the size of the objects in memory I would think they are a bit large to
> put on the stack and should be better of on the heap. Which would mean I
> should use classes.
>
> Any ideas about what would be best?
>
> TIA
>
> Yves
>
>[/color]

[Peter Rilling]

Re: design question : struct or class

It sounds like your object has the potential of being quite large. Remember
that structures are allocated on the stack, which is finite. I don't know
the stack size off the top of my head.

"phoenix" <patient0@skyne tWORK.be> wrote in message
news:O1efil54DH A.1948@TK2MSFTN GP12.phx.gbl...[color=blue]
> Hello,
>
> I've got a design question. I need to keep track of some variables and I[/color]
am[color=blue]
> planning to put them inside a class or struct. Basically I'm talking about
> 10 bools, 20 ints and 2 arrays of ints. The size of the arrays would[/color]
depend[color=blue]
> on some external value (going from 0 to around 1000 max). I would have an
> array of max 255 of these classes/structs (in most cases it will be less
> then 5 however)
>
> Since there's no real business logic my choice would be structs. But[/color]
looking[color=blue]
> at the size of the objects in memory I would think they are a bit large to
> put on the stack and should be better of on the heap. Which would mean I
> should use classes.
>
> Any ideas about what would be best?
>
> TIA
>
> Yves
>
>[/color]

[Jeff Louie]

Re: design question : struct or class

Pheonix... To be clear, if you add structures to a .NET _collection_,
they
will be boxed anyway.

Regards,
Jeff[color=blue]
>array of max 255 of these classes/structs (in most cases it will be[/color]
less
then 5 however)<


*** Sent via Developersdex http://www.developersdex.com ***
Don't just participate in USENET...get rewarded for it!

[Jeff Louie]

Re: design question : struct or class

Peter... To be clear, structures can be inlined if they are part of a
class or
?array.

Regards,
Jeff[color=blue]
>Remember that structures are allocated on the stack, which is finite.<[/color]

*** Sent via Developersdex http://www.developersdex.com ***
Don't just participate in USENET...get rewarded for it!

[codymanix]

Re: design question : struct or class

> I've got a design question. I need to keep track of some variables and I
am[color=blue]
> planning to put them inside a class or struct. Basically I'm talking about
> 10 bools, 20 ints and 2 arrays of ints. The size of the arrays would[/color]
depend[color=blue]
> on some external value (going from 0 to around 1000 max). I would have an
> array of max 255 of these classes/structs (in most cases it will be less
> then 5 however)[/color]

You should *Always* use classes. structs are only needed in very rare
circumatances which isn't the case.

--
cody

[Freeware, Games and Humor]
www.deutronium.de.vu || www.deutronium.tk

[ozbear]

Re: design question : struct or class

On Fri, 30 Jan 2004 00:56:36 +0100, "codymanix"
<dont.spam.me.d eutronium@gmx.d e> wrote:
[color=blue][color=green]
>> I've got a design question. I need to keep track of some variables and I[/color]
>am[color=green]
>> planning to put them inside a class or struct. Basically I'm talking about
>> 10 bools, 20 ints and 2 arrays of ints. The size of the arrays would[/color]
>depend[color=green]
>> on some external value (going from 0 to around 1000 max). I would have an
>> array of max 255 of these classes/structs (in most cases it will be less
>> then 5 however)[/color]
>
>You should *Always* use classes. structs are only needed in very rare
>circumatance s which isn't the case.
>[/color]

Rubbish....anyo ne saying "always" do or don't do X is practicing
religion, not programming. Structs have their proper place in the
programming paradigm, just as classes do. Knowing which to use and
when defines the difference between a programmer and a zealot/ostrich.

Oz

[Guest]

Re: design question : struct or class

Use them whatever best way suits you. Scew the fanboys.

Same for any aspect of software. Do what works best for you.


"ozbear" <ozbear2@yahoo. com> wrote in message
news:401a31e1.1 431256578@news-server...[color=blue]
> On Fri, 30 Jan 2004 00:56:36 +0100, "codymanix"
> <dont.spam.me.d eutronium@gmx.d e> wrote:
>[color=green][color=darkred]
> >> I've got a design question. I need to keep track of some variables and[/color][/color][/color]
I[color=blue][color=green]
> >am[color=darkred]
> >> planning to put them inside a class or struct. Basically I'm talking[/color][/color][/color]
about[color=blue][color=green][color=darkred]
> >> 10 bools, 20 ints and 2 arrays of ints. The size of the arrays would[/color]
> >depend[color=darkred]
> >> on some external value (going from 0 to around 1000 max). I would have[/color][/color][/color]
an[color=blue][color=green][color=darkred]
> >> array of max 255 of these classes/structs (in most cases it will be[/color][/color][/color]
less[color=blue][color=green][color=darkred]
> >> then 5 however)[/color]
> >
> >You should *Always* use classes. structs are only needed in very rare
> >circumatance s which isn't the case.
> >[/color]
>
> Rubbish....anyo ne saying "always" do or don't do X is practicing
> religion, not programming. Structs have their proper place in the
> programming paradigm, just as classes do. Knowing which to use and
> when defines the difference between a programmer and a zealot/ostrich.
>
> Oz
>[/color]

[peter x]

Re: design question : struct or class

Hi there,

The main difference is that a 'class' is an object type and a struct is a
'value' type. When it comes to assignment and parameter passing its
important to know the difference:


Assignment
-------------
myObject o1 = new myObject()
myObject o2 = new myObject()
o1 = o2

Objects are 'reference' types and are really pointers to an address in
memory where values are stored. In the above example space is allocated for
two myObject types. o1 points to the first myObject type and o2 points to
the second myObjects type. Because objects are reference types, its not the
values held in o2 that are copied into o1 but rather the address in memory
that is pointed too by o2. Consequently, 'o1 = o2' has the effect of
pointing both o1 and o2 at the same place in memory and changes to o1 will
change o2 and vice versa. If no references remain to the memory allocated
for the original o1 object it will eventually be garbage collected.

myStruct s1 = new myStruct()
myStruct s2 = new myStruct()
s1 = s2

Structs are 'value' types and are very much like ints or floats. In the
above example space is allocated for s1 and s2. s1 is the first myStruct
type and s2 is the second myStruct type. Because structs are value types,
its not the reference for s2 that is copied into s1 but the values.
Consequently, 's1 = s2' has the effect of maintaining two seperate areas in
memory with the same values. Sometimes this is what you want and sometimes
it isn't. For example, If your struct type contains a nested object it isn't
the values of the nested object that are copied but rather the reference. In
the case of 's1 = s2', you will have two seperate blocks of memory which
contain the same values but the object reference in both will point to the
same place in memory. To find out more about avoiding this problem look for
help and shallow vs deep copying.


Parameter Passing
---------------------

When objects are passed to a method, they are passed by reference. This
means that any changes made to the object within the method will remain once
the method had been completed.

When structs are passed to a method, they are passed by value. This means
that the system makes a copy is made and changes made to the struct will not
remain when the method is complete. You can get round this by returning the
copied struct and assigning it to a variable but there is an obvious over
head in working with copies.


Summary
----------

The choice of whether to use a class or a struct is entirely down to you,
both have there place. However, because of the overheads involved in passing
by value and the added complexity of nested objects, I uses classes most of
the time. I only use structs when the offer me exactly what i need. I hope
this helps and that my explanation was too confusing and if I am wrong on
any point my apologies in advance.


Happy coding, Peter




"codymanix" <dont.spam.me.d eutronium@gmx.d e> wrote in message
news:%23M3XdPs5 DHA.1948@TK2MSF TNGP12.phx.gbl. ..[color=blue][color=green]
> > I've got a design question. I need to keep track of some variables and I[/color]
> am[color=green]
> > planning to put them inside a class or struct. Basically I'm talking[/color][/color]
about[color=blue][color=green]
> > 10 bools, 20 ints and 2 arrays of ints. The size of the arrays would[/color]
> depend[color=green]
> > on some external value (going from 0 to around 1000 max). I would have[/color][/color]
an[color=blue][color=green]
> > array of max 255 of these classes/structs (in most cases it will be less
> > then 5 however)[/color]
>
> You should *Always* use classes. structs are only needed in very rare
> circumatances which isn't the case.
>
> --
> cody
>
> [Freeware, Games and Humor]
> www.deutronium.de.vu || www.deutronium.tk
>
>[/color]

[peter x]

Re: design question : struct or class

Hi there,

The main difference is that a 'class' is an object type and a struct is a
'value' type. When it comes to assignment and parameter passing its
important to know the difference:


Assignment
-------------
myObject o1 = new myObject()
myObject o2 = new myObject()
o1 = o2

Objects are 'reference' types and are really pointers to an address in
memory where values are stored. In the above example space is allocated for
two myObject types. o1 points to the first myObject type and o2 points to
the second myObjects type. Because objects are reference types, its not the
values held in o2 that are copied into o1 but rather the address in memory
that is pointed too by o2. Consequently, 'o1 = o2' has the effect of
pointing both o1 and o2 at the same place in memory and changes to o1 will
change o2 and vice versa. If no references remain to the memory allocated
for the original o1 object it will eventually be garbage collected.

myStruct s1 = new myStruct()
myStruct s2 = new myStruct()
s1 = s2

Structs are 'value' types and are very much like ints or floats. In the
above example space is allocated for s1 and s2. s1 is the first myStruct
type and s2 is the second myStruct type. Because structs are value types,
its not the reference for s2 that is copied into s1 but the values.
Consequently, 's1 = s2' has the effect of maintaining two seperate areas in
memory with the same values. Sometimes this is what you want and sometimes
it isn't. For example, If your struct type contains a nested object it isn't
the values of the nested object that are copied but rather the reference. In
the case of 's1 = s2', you will have two seperate blocks of memory which
contain the same values but the object reference in both will point to the
same place in memory. To find out more about avoiding this problem look for
help and shallow vs deep copying.


Parameter Passing
---------------------

When objects are passed to a method, they are passed by reference. This
means that any changes made to the object within the method will remain once
the method had been completed.

When structs are passed to a method, they are passed by value. This means
that the system makes a copy is made and changes made to the struct will not
remain when the method is complete. You can get round this by returning the
copied struct and assigning it to a variable but there is an obvious over
head in working with copies.


Summary
----------

The choice of whether to use a class or a struct is entirely down to you,
both have there place. However, because of the overheads involved in passing
by value and the added complexity of nested objects, I uses classes most of
the time. I only use structs when the offer me exactly what i need. I hope
this helps and that my explanation was too confusing and if I am wrong on
any point my apologies in advance.


Happy coding, Peter




"codymanix" <dont.spam.me.d eutronium@gmx.d e> wrote in message
news:%23M3XdPs5 DHA.1948@TK2MSF TNGP12.phx.gbl. ..[color=blue][color=green]
> > I've got a design question. I need to keep track of some variables and I[/color]
> am[color=green]
> > planning to put them inside a class or struct. Basically I'm talking[/color][/color]
about[color=blue][color=green]
> > 10 bools, 20 ints and 2 arrays of ints. The size of the arrays would[/color]
> depend[color=green]
> > on some external value (going from 0 to around 1000 max). I would have[/color][/color]
an[color=blue][color=green]
> > array of max 255 of these classes/structs (in most cases it will be less
> > then 5 however)[/color]
>
> You should *Always* use classes. structs are only needed in very rare
> circumatances which isn't the case.
>
> --
> cody
>
> [Freeware, Games and Humor]
> www.deutronium.de.vu || www.deutronium.tk
>
>[/color]

[rhavaldar at shodaka dot net]

Re: design question : struct or class

I would suggest grouping your 'data' into structs/classes (based on the
your need for value type/reference type. You would potentially
end up w/ many of these structures and not just 'one' global placeholder.

For more, check out the structural design patterns @ c2 -

http://c2.com/cgi/wiki?CategoryStructuralPatterns

- raghu


codymanix wrote:
[color=blue][color=green]
>>I've got a design question. I need to keep track of some variables and I[/color]
>
> am
>[color=green]
>>planning to put them inside a class or struct. Basically I'm talking about
>>10 bools, 20 ints and 2 arrays of ints. The size of the arrays would[/color]
>
> depend
>[color=green]
>>on some external value (going from 0 to around 1000 max). I would have an
>>array of max 255 of these classes/structs (in most cases it will be less
>>then 5 however)[/color]
>
>
> You should *Always* use classes. structs are only needed in very rare
> circumatances which isn't the case.
>[/color]

[Jon Skeet [C# MVP]]

Re: design question : struct or class

peter x <lad4bear@boltb lue.com> wrote:

<snip>
[color=blue]
> When objects are passed to a method, they are passed by reference.[/color]

No they are not. "Pass by reference" has a very specific meaning, and
it *doesn't* apply here (unless you use the ref modifier). There is a
big difference between a reference being passed by value (which is what
actually happens) and a parameter itself being passed *by* reference.

See http://www.pobox.com/~skeet/csharp/parameters.html for more
information.

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

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

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

[peter x]

Re: design question : struct or class

I stand corrected :) Although I'm not sure I totally understand your
response. Can you send me an example to help me clarify. Apart from this
point was the rest of the assessment correct? specifically the point about
the overhead involved in passing by value. I may need to reassess how I
program

Cheers, Peter


"Jon Skeet [C# MVP]" <skeet@pobox.co m> wrote in message
news:MPG.1a85aa 6c3b3ea02598a02 1@msnews.micros oft.com...[color=blue]
> peter x <lad4bear@boltb lue.com> wrote:
>
> <snip>
>[color=green]
> > When objects are passed to a method, they are passed by reference.[/color]
>
> No they are not. "Pass by reference" has a very specific meaning, and
> it *doesn't* apply here (unless you use the ref modifier). There is a
> big difference between a reference being passed by value (which is what
> actually happens) and a parameter itself being passed *by* reference.
>
> See http://www.pobox.com/~skeet/csharp/parameters.html for more
> information.
>
> --
> 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: design question : struct or class

peter x <lad4bear@boltb lue.com> wrote:[color=blue]
> I stand corrected :) Although I'm not sure I totally understand your
> response. Can you send me an example to help me clarify.[/color]

Sure.

Here's what pass by value means:
The value of the expression in the actual parameter (i.e. in the
calling code) becomes the value of the new variable which is the formal
parameter (i.e. in the method itself).

Here's what pass by reference means:
Only a variable (non-read only) can be used as a pass by reference
parameter, and the formal parameter variable in the called method is
effectively aliased with the actual parameter - they are different
names for the same memory location, so changing the value of one
changes the value of the other.

Note that nowhere in those definitions is the type of the parameter
(i.e. reference type or value type) used. Both value type parameters
and reference type parameters can be passed by value or by reference,
and in both cases the default is "by value". The only twist here is
understanding that the value of a reference type expression (or
variable) isn't an object - it's a reference. So, if I do:

string x = "hello";
Foo (x);
....
void Foo (string y)
{
....
}

the string itself isn't passed - the string *reference* (the value of
x) is passed by value.

For more examples etc, have another look at the article I linked to
before.
[color=blue]
> Apart from this point was the rest of the assessment correct?[/color]

As far as I saw, yes - I only skimmed it though. (The usual terminology
is reference type rather than object type though.)
[color=blue]
> specifically the point about
> the overhead involved in passing by value. I may need to reassess how I
> program[/color]

Unlikely. You should indeed by using classes most of the time, and
passing a reference by value is indeed cheaper than passing a large
value type value.

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

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

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

[Ravichandran J.V.]

Re: design question : struct or class

Yes, if the memory that the object is going to occupy is large, the
usual choice is a class but, if the object is going to contain only
data-members, then it is beter to use a struct as a class is generally
resolved as a container for logic apart from data-members.

with regards,


J.V.Ravichandra n
- http://www.geocities.com/
jvravichandran
- http://www.411asp.net/func/search?
qry=Ravichandra n+J.V.&cob=aspn etpro
- http://www.southasianoutlook.com
- http://www.MSDNAA.Net
- http://www.csharphelp.com
- http://www.poetry.com/Publications/
display.asp?ID= P3966388&BN=999 &PN=2
- Or, just search on "J.V.Ravichandr an"
at http://www.Google.com

*** Sent via Developersdex http://www.developersdex.com ***
Don't just participate in USENET...get rewarded for it!