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The built-in value types does not need a constructor, as the compiler already knows how to create the values. For any user defined value type, though, you need a constructor to create a value.
A structure always has a parameterless constructor, that you can use to create a zero initalised value. If you declare a structure as a member variable of a class, it will also be zero initalised. If the structure is mutable (like the Point structire), you can then change the members of the structure value. If the structire is not mutable, using a constructor is the only way to create a value.
A constructor for a structure is a bit different from a constructor for a class, as it doesn't allocate memory for an object instance, it just returns the created value. A class constructor returns the reference to the allocated object, while a structure constructor returns the actual value.
The new keyword is used to call a constructor, regardless if you use it on a structure or a class. You can't call a constructor without the new keyword.
---
It's amazing to see how much work some people will go through just to avoid a little bit of work.
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1. why do overloaded operators have to be static?
2. why do they have to be unary?
3. why does the overloaded operator being static imply that they are never polymorphic? (my attempt at answering #3: is it because since they are static you don't need an instance and therefore it can never change behaviour at runtime since you don't need an instance (just the class) to call the operator... meaning there is no opportunity to override this operator on derived class since it is class-based not instance based.
4. why is it recommended that operators are overloaded only on value types?
5. finally, why would i implement the postfix operator differently for a class than for a struct?
ps. these aren't assignment questions, i am trying to learn c# without a book. what books wou=ld you recommend? i am thinking of buying 3: 1) clr via c# 2) visual c# 2005 by Francesco Balena 3) inside c#
tia!
-- modified at 7:25 Thursday 21st December, 2006
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j11Software wrote: 1. why do overloaded operators have to be static?
They get passed the values upon which to act -- e.g. a+b ==> operator+(a,b)
j11Software wrote: 2. why do they have to be unary?
They don't, they may be binary.
j11Software wrote: 3. why does the overloaded operator being static imply that they are never polymorphic?
Static methods can't be virtual.
j11Software wrote: 4. why is it recommended that operators are overloaded only on value types?
Never heard of that. Use them wherever they make sense.
j11Software wrote: 5. finally, why would i implement the postfix operator differently for a class than for a struct?
What's a postfix operator?
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The characteristics of operator overloading are what they are by design.
One of the main goals must have been to avoid confusion.
Hence, overloaded operators are:
- static (int+int performs addition irrespective of numeric values, so obj+obj should
do that too)
- either unary or binary (you can define obj-obj as well as -obj)
- similar in precedence as for numeric operations (* before +)
All of this makes the source code stays readable and intuitive.
So operator overloading is just fine for classes such as complex numbers,
big integers, etc, and anything really fancy is prohibited.
For a good example, take a look at http://www.codeproject.com/csharp/biginteger.asp[^]
Luc Pattyn
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Hi all
I am developing one installation wizard. I have one issue. If i click the next button I made the current form visible = false and creating instance for the next from and showing the form. There problem I facing is, I dont know how to show the previous form by hidding the current form. Can anybody help me please....
Thanks
kesavan
kesavan
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Hello,
You could use a property Form1 in youre Form2, which is set by Form1.
private Form myform1;
public Form MyForm1
{
get
{
return myform1;
}
set
{
myform1 = value;
}
}
{
MyForm1.Visible=true;
MyForm1=null;
this.Close();
}
{
Form2 form2 = new Form2()
form2.MyForm1 = this;
}
All the best,
Martin
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Thank you so much martin. I have done with your help
kesavan
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Why don't you send a reference of form1 throught the constructor of form2.
Example:
the constructor of form2 is:
<br />
private Form1 parentForm;<br />
<br />
public void Form2(From1 form)<br />
{<br />
parentForm = form1;<br />
}<br />
and when u initialize the second form to call it in form1,
use this:
<br />
Form2 form2 = new Form2(this);<br />
form2.show();<br />
now you can use the visible property of the form1 from form2 and u can unhide it by simply writting this:
<br />
parentForm.Visible = true;<br />
Good luck
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Thank you so much smart. I have done with your help
kesavan
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depending how many forms you are going to end up with. I would be tempted to make a control class that holds the data and controls which forms get loaded / unloaded at which point. If you are only ever going to have 2 forms it's probably not worth it but if you don't know how many forms you might end up with or which order people are going to want them in it's probably worth the extra effort up front.
Russ
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hi
i want to use oledbCommandBuilder for Insert,Update,Delete Commands dinamically, but how to use it ?
thanks
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Hi,
I have a Peculiar problem in my C# Windows application. The scenario is, we have a windows application running in windows Xp environment, its main operation is copy the Employee word Document file from one employee machine and paste it to the other employee. It’s purely a File copy and Paste operation. To do this we shared One drive in all the employee machine with full access writes to every in the network. So my application go to that particular shared drive copy all document from that location and paste it in to other shared drive. This is working fine in the current environment.
My problem is, now that all shared drives permissions are changed and restricted to Read only permission, every one in the network they only read the file in the network shared drive, they can not paste any file in to that drive. This is to avoid other employee miss use and security purpose. After this implementation my application is not copying the file from that shared drive and pasting. It’s throwing the error unauthorized access or don’t have a permission to access folder.
My question is how to give permission to the application to access that folders and copy to other network shared drive even if the application runs in windows user login mode. This application runs in entire employee machine. Once they login to the system it starts running. Please suggest me the best way to over come this issue
Thanks in advance.
By,
Rajasekarn Shan
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You should probably use TCP/IP sockets to send the file across. When a file needs to be copied you can establish a connection with the particular machine and send the file, the receiving machine can save the file into a configured folder.
Tarakeshwar Reddy
MCP, CCIE Q(R&S)
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Hi tarakeshwar,
can you provide me a little more about TCP/IP? some examples if possible.
By,
Rajasekaran.S
Rajasekarn Shan
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Hi there,
I am currently creating a web application in c# 2005, on my search form i would like to display an animated gif image while busy doing the search in the sql database.
As soon as the user clicks the search button i want the image to become visible and then as soon as the gridview got binded with the results, i want the image to be invisible again.
Now the problem is that the image does not become visible at all 
mmmm i dunno where to start finding the problem cause it does run the code but does not actually do it lol.
I am thinking i should probably use like "sleep" or threads but thats some weird stuff for me as i am still beginner. Is there any other solution to this problem?
Thanks in advance
Regards
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Hello,
I think the problem is that you are running the control with the gif in the same threat (which is busy) where you are doing the search.
You could do a control.Refresh();, after you set Visible=true.
But it would only show the not- or rarely moving gif I think.
All the best,
Martin
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Hi All,
I am using VS.NET 2005 and using C#.net.
I want to develop a functionality as follows.
when I run my application , it should create a Icon in system tray. When I close the application it's instance should be running in the background and Icon should be displayed in the system tray. Again when i click on my applications shortCut Icon on desktop , not the icon from system tray, it should bring forward the already running instance of my application in the background.
thnx in advance
Praveen
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Have a look at this article[^]
Tarakeshwar Reddy
MCP, CCIE Q(R&S)
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Hello everyone,
How can I find if two controls intersect or not ?
Best regards...
.:: Something is Wrong ::.
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if (control1.Bounds.IntersectsWith(control2.Bounds))
...
That should do it.
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Hi =),
I have class that works with a Generic.Dictionary and now i want to access the elements by an index.
Is there a way i can do this ? ...or are there other classes where i can access the elements by an
index and provides the same functionality like the Generic.Dictionary?
I already found the Generic.SortedList, but there my listing will be sorted and i dont need/want that =/
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Hello,
If you don't need the access per key functionality at, you should use an ArrayList. (System.Collections)
All the best,
Martin
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