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That is a proven tactic when you're absolutely clueless about what you are doing.
A skill commonly found in managers  s
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Dave Kreskowiak wrote: Measuring the speed of an activity in FLOPS is like measuring the speed of a car in liters of Gas per hour.
Now you cause me to doubt my comprehension of this. FLOPS would be specific and consistent on the particular system yes? So doesn't work for the OPs statement since ArrayList processing is going to run at the same per second rate as anything else on that system, yes? However a car operates at a variable rate of speed so, my head esplode like a liter of Gas! 
led mike
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ignorance == incompetence?
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I'm also having problems comprehending how much floating point arithmetic .Net needs to copy memory. 
I'm largely language agnostic
After a while they all bug me 
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I'm also having problems comprehending how much floating point arithmetic .Net needs to perform to copy an 8 byte pointer
I'm largely language agnostic
After a while they all bug me
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I'm also having problems comprehending how much floating point arithmetic .Net needs to perform to copy a pointer
I'm largely language agnostic
After a while they all bug me
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Crud, it kept timing out
I'm largely language agnostic
After a while they all bug me
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when passing the information from method to method, an arraylist is not the most efficient taking up to 60,000 flops to pass the information therefore arrays are faster.
That's not only wrong, it's also wrong. 
When passing information to a method, it takes exactly the same time to pass an Array as an ArrayList. They are both objects, so what you pass to the method is a reference to the object. A reference is just a pointer, so on a 32 bit system it's only four bytes to copy.
Whatever you do with an ArrayList, there are no floating point operations going on. You could say that an operation would use the equivalent of 60000 flops, but it's hardly useful to measure operations that doesn't use floating point operations in flops.
Also, there are so much more to consider than the raw processor load. You have so many other factors that affect the performance, like cache sizes, memory bandwidth, data bus width, data aligning, instruction pairing... And there are also other things to consider than just performance, like robustness and scalability.
Despite everything, the person most likely to be fooling you next is yourself.
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I think I made the same point, errr, 4 times
I'm largely language agnostic
After a while they all bug me
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I created a bitmap object and used it to draw a 2D terrain programatically on a form. Then I also added a picturebox control to display an image near the terrain.
However, the picturebox control is blocking out part of the bitmap.
How do I make the bitmap "cover" part of the picturebox control instead?
Is there a "layers" method which the form can use to draw one bitmap over another control?
Edit/Delete Message
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If by saying "the picturebox control is blocking out part of the bitmap." you mean it shows some of the picture then set the picturebox control's (Image I think) property to Stretch.
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Drawing an image to the form itself will always place the image behind the controls.
Just because we can; does not mean we should.
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Hi guys,
I am trying to validate if a user exists in a database but I get an error.
The error message that I get is:
Syntax error in string in query expression 'UserName = '"userName'
"userName = username in textBox"
Can somebody tell me where I'm going wrong here please?
private void btnchkUser_Click(object sender, EventArgs e)
{
string sql = "SELECT UserName FROM Users WHERE UserName = '" + txtboxUserName.Text;
OleDbCommand cmdb = new OleDbCommand(sql, conn);
conn.Open();
OleDbDataReader drr = cmdb.ExecuteReader();
if (drr.Read() == true)
{
MessageBox.Show("User already exist", "User already exist", MessageBoxButtons.OK);
return;
}
conn.Close();
}
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string sql = "SELECT UserName FROM Users WHERE UserName = '" + txtboxUserName.Text;
The error tells you what the problem is:
Syntax error in string in query expression 'UserName = '"userName'
Here is the correct version of your query:
string sql = "SELECT UserName FROM Users WHERE UserName = '" + txtboxUserName.Text + "'";
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Brilliant. That works 100%.
Thanks mate
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Please don't do this - you are leaving your code wide open to a SQL Injection attack. Try reading this[^] article.
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I have a question that i can't seem to answer. Is there a dependence between a point and a pixel (for example 1 point = 2 pixels). I need to know this because i want to make the width of a PictureBox so it can hold a string.
The font i am using is Arial 8 points.
When try with pictureBox.Width = line.Length * 8; the PictureBox is wider than the string.
How can i find the length of the string in pixels?
Still learning...
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Thank you very much!
Still learning...
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Hi,
I have the following:
namespace Server.Layer1
{
public class BaseClass : MarshallByRefObject
{
public enum SomeEnum
{
Zero = 0,
One = 1
}
abstract public IMyInterface CreateImplmentor(SomeEnum anEnum);
}
}
Here is IMyInterface
namespace Server.Layer2
{
public interface IMyInterface
{
bool Save(Student aStudent);
event AnEventHandler SomethingHappened;
}
public delegate void SomethingHappened(object sender, EventInfo e);
}
I have registered the class which implements the BaseClass functionality and register it using a
console application host. Compiles fine.
I have a client but when it connects to BaseClass, exception is thrown at this line:
BaseClass classReceived = (BaseClass ) RemotingServices.Connect(typeof(BaseClass),
"http://localhost:65100/RemoteClass");
Exception is: "Trying to create a proxy to an unbound type."
Student is Serializable. BaseClass is MarshalByRefObject and so is the class which implements the IMyInterface. I am not sure what the problem could be. If a class inherits from MarshalByRefObject and has delegates or events, do they need any special attributes?
Please help,
Thanks
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Hi,
I have an issue where I get a pointer to unmanaged data (along with the number of bytes allocated) from a device and I need to perform a checksum on this data. While I have found plenty of information to pin a managed array and feed that to a C library call, I have been unable to find any methods for going to other way around.
public static byte[] MD5Checksum(unsigned char* data, int dataLength){<br />
<br />
byte[] unmanagedWrapper = MagicalMethodToWrapUnmanagedArray(data, dataLength);<br />
<br />
return System.Security.Cryptography.MD5.Create().ComputeHash(unmanagedWrapper);<br />
}
Thanks in advance!
B
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On a windows for, after clicking a button, I add a class Student to an ArrayList with
ArrayList Grade10 = new ArrayList();
Grade10.Add(new Student(a, b, c, d, e); //Student declared as public class elsewhere
This seem to work fine.
However, I then want to load the items in a Listbox when another button is clicked. I use
foreach (Student i in Grade10)
lbxShow.Items.Add(" " + i);
I get message that Grade10 does not exist in this context. If I declare Grade10 again in this event it appears that the ArrayList is empty - program runs, no errors, empty ListBox.
All samples I find refer to console apps. These work for me but I cannot sort out the windows form - my first attempt at C#, I've been using Delphi for ages.
Seems I have to declare ArrayList Grade10 somewhere else (global?) so it is visible inside the second button event as well?
Much appreciate someone showing me the way.
Hannes
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Hi,
it has nothing to do with console app vs windows app.
the problem is Grade10 is "not in scope" where you try to use it, otherwise
"declaring Grade10 again" would result in a compile-time error.
Anyway, declaring again, or performing one more new, never solves anything, since then
you are stuck with an object that is different from the original, so does not hold its
content, etc.
If you want detailed help, publish the actual code, not pieces of it.
Luc Pattyn [Forum Guidelines] [My Articles]
This month's tips:
- before you ask a question here, search CodeProject, then Google;
- the quality and detail of your question reflects on the effectiveness of the help you are likely to get;
- use PRE tags to preserve formatting when showing multi-line code snippets.
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Yep sounds like a scope issue. Not sure where you actually have declared Grade10 and where you've tried to use it but thats a safe bet as to what your problem is, but I can't help you without more code.
Sidenote: Use List instead of ArrayList, they're better for you
He who makes a beast out of himself gets rid of the pain of being a man
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