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what is the size of reference variable
“You will never be a leader unless you first learn to follow and be led.”
–Tiorio
"Coming together is a beginning, staying together is progress, and working together is success." Henry Ford
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Size doesn't matter.....
forgot the joke icon
Never underestimate the power of human stupidity
RAH
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This was the question asked me in an interview.
“You will never be a leader unless you first learn to follow and be led.”
–Tiorio
"Coming together is a beginning, staying together is progress, and working together is success." Henry Ford
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OK - that has to be a contender for daftest technical question you're likely to receive in an interview. Unless you're going for a really senior post, I wouldn't expect that you'd carry this round in your head. I certainly wouldn't mark you down for not knowing it.
"WPF has many lovers. It's a veritable porn star!" - Josh Smith As Braveheart once said, "You can take our freedom but you'll never take our Hobnobs!" - Martin Hughes.
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That's actually a very good question and I think its 12 bytes (on a 32 bit system). 4 of those are the pointer or the reference, then there's some internal thing (garbage collection?) and I think there's a synchronisation part too.
Of course, that's not taking into account whatever you've got on the heap which actually represents your object.
I do know for sure that if you're storing vast collections of simple objects it's better to use structs rather than classes. This saves that overhead.
Regards,
Rob Philpott.
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Rob Philpott wrote: I think its 12 bytes
IMO at run-time a reference is just a pointer, no more no less, hence 4 or 8B.
Luc Pattyn [Forum Guidelines] [My Articles]
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Agreed, just 4/8 bytes on the stack. But on the heap you get the extra eight bytes on top of the object itself. I think - not certain.
Someone, somewhere did a wonderful job of explaining it all here on CP.
Regards,
Rob Philpott.
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Thanks. Too long to read right now.
In the mean time I think we understood the question in different ways.
"What is the size of a reference variable?" to me means "What is the size of a reference?" (hence 4 or 8B) and not "What is the size of an object?". Which I guess gets dealt with in the article; I hope it also mentions objects get aligned in memory, I think to a 32B boundary. So, assuming that is correct, the smallest object costs 32B of heap space.
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Luc Pattyn wrote: So, assuming that is correct, the smallest object costs 32B of heap space.
At the risk of really being quite boring, I was playing around with that the other day, trying to work out how much space a boolean takes as a class member variable.
Turns out the first one takes 32 bits, the second no bits, the third no bits, the fourth no bits, the fifth 32 again, etc. etc.
So, sort of one byte collectively rounded up to the nearest 32 bit word.
Regards,
Rob Philpott.
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No surprise here. That is due to padding (inserting unused bytes, or rounding up the address), exactly like what happens when storing bytes in a C/C++/C# structure. By default elements of a struct (and the overall size of a struct) get word-aligned to prevent an access to the next 16-bit or larger quantity to cause a performance hit or an exception.
Luc Pattyn [Forum Guidelines] [My Articles]
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Cool.
Regards,
Rob Philpott.
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Then why is it such a pain in the ass to convert references to IntPtr and vice versa (for using with platform invoke). As I understand it - IntPtr is a typical substitute for a general unmanaged pointer (int*, void*, ...), so why can't one use something like
SomeReferenceType instance;<br />
PInvokeCall((IntPtr) instance);
where PInvokeCall has signature
void PInvokeCall(IntPtr param);
No trolling, I am really curious about this.
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A small object (small enough to be in a regular heap, not the large-object-heap) is a moving target: when the GC runs it can move it around to perform heap compaction. Managed code is fine with this, however your native code would not be aware of this, so the pointer could become invalid, unless the object got pinned first. That is exactly what the ref-to-ptr convertors ("fixed", GCHandle, Marshal) do.
Luc Pattyn [Forum Guidelines] [My Articles]
The quality and detail of your question reflects on the effectiveness of the help you are likely to get.
Show formatted code inside PRE tags, and give clear symptoms when describing a problem.
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Hi Guy
How can i Drag email of Outlook Express to Winform and Save to file .eml.
I can do it with Outlook 2003 and save to file .msg.
Anybody help me?![Rose | [Rose]](https://codeproject.global.ssl.fastly.net/script/Forums/Images/rose.gif)
Thanks and best regards
Thien Nguyen
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i'm looking hard for an answer to this as it is critical that I can drag from outlook express to winform app c#
mail me if you find and answer.
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Hey guys, for some reason this stupid TCP server doesn't loop after a client disconnects from it. How can I have it continue to loop so when people do disconnect from it, it continues to accept connections. Here is the code.
using System;
using System.Text;
using System.Net;
using System.Net.Sockets;
public class serv
{
public static void Main()
{
int c = 1234;
try
{
IPAddress ipAd = IPAddress.Parse("69.10.61.145"); //use local m/c IP address, and use the same in the client
/* Initializes the Listener */
TcpListener myList = new TcpListener(ipAd, 7575);
/* Start Listeneting at the specified port */
myList.Start();
Console.WriteLine("Login Server is running.");
Console.WriteLine("Connection :" + myList.LocalEndpoint);
Console.WriteLine("Waiting for logins...");
Console.WriteLine("================================");
Socket s = myList.AcceptSocket();
Console.WriteLine("Connection accepted from: " + s.RemoteEndPoint);
byte[] b = new byte[100];
int k = s.Receive(b);
Console.WriteLine("Login Attempt Recieved from: " + s.RemoteEndPoint);
for (int i = 0; i < k; i++)
Console.Write(Convert.ToChar(b[i]));
ASCIIEncoding asen = new ASCIIEncoding();
s.Send(asen.GetBytes("Login is invalid." + s.RemoteEndPoint));
Console.WriteLine("\nAccess Denied.");
Console.ReadLine();
return;
/* clean up */
}
catch (Exception e)
{
Console.WriteLine("Error..... " + e.StackTrace);
Console.ReadLine();
}
}
}
[X] 100% HTML
[ ] 100% PHP
[ ] 100% C#
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Either look up the async methods or wrap a while loop over the hart of the operation.
I personall recommend the async methds and they also nearly force you to do all the work in seperate methods, which actually comes in handy when you get used to it.
For the while loop, consider using a global bool value which you change when stopping to listen.
The while loop should cancel then and your application should continue.
Though, this doesn't really work as you may want to depending on how you build you loop.
In most cases it will still wait for a last connection to be made before it will finally break.
Start the loop before AcceptSocket call and end it when you're done, in this case below the Access Denied output.
I hope this helps a bit, TCP/IP is always confusing at the start...
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I just wrapped while(true) around it, will that work? Also can you take a look at my other thread. its very important.
[X] 100% HTML
[ ] 100% PHP
[ ] 100% C#
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I'd seriously recommend creating a new thread to handle the connection after you've accepted the incoming connection - that's the usual way these bits of code work. One thread just sits there and accepts connections, each time one comes in the socket is passed to a new thread to handle the conversation and the original thread carries on listening for subsequent connections.
What sort of server can only handle a single incoming connection? Also, take a look at TCPClient, it provides nicer access than Socket.
Regards,
Rob Philpott.
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Hi,
Look at the following article[^], I think it might help you alot.
Kind regards,
The only programmers that are better C# programmers, are those who look like this -> ![Green Alien | [Alien]](https://codeproject.global.ssl.fastly.net/script/Forums/Images/alien.gif) |
Programm3r
My Blog: ^_^
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Is there a way to do it?
IE:
30000
I want it to be 30 000
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You can use the .ToString() method to make it to a string.
There is a regexp function to do such a thing, but I forgot about it.
However, here is snippet that should do the trick aswell.
int number = 3000000;
int lengthPerSplit = 3;
string splitText = " ";
string result = number.ToString();
for (int index = result.Length - lengthPerSplit; index > 0; index -= lengthPerSplit)
result = result.Substring(0, index) + splitText + result.Substring(index, result.Length - index);
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try this as a simpler solution, just keep adding sets of 3 #s
string.Format("{0:### ### ###.00}", 30000000);
Never underestimate the power of human stupidity
RAH
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