C# Discussion Boards - CodeProject

Anonymous27-Aug-05 12:25

27-Aug-05 12:25

Thanks Muhammad,

I have read about P/Invoke...

My problem now is with marshalling the data between the managed and unmanaged code...

The unmanaged function that I want to call has the following input parameter of type CvContourRetrievalMode that takes only 4 values ,either CV_RETR_TREE ..etc

I don't know if it would be correct to use an enum in this case?

Thanks again,
E.A.

Tutorial on writing and reading configuration file

Fredy27-Aug-05 10:06

Fredy

27-Aug-05 10:06

Hi I'me new to C# and about to finish my first example program. It is a command line program (no gui). What I want to do now is adding a form for configuration values. These values should be written into an xml file and should be read by the program afterwards.
I heard about system.configuration and its read capabilities. But I didn't heard anything about writing to sections.
Now my question: Where can I get tutorials or other informations about writing and reading to/from configuration files?

Thanks and regards Fredy

Re: Tutorial on writing and reading configuration file

Mohamad Al Husseiny27-Aug-05 10:23

Mohamad Al Husseiny

27-Aug-05 10:23

Look at
An extension for a Configuration Settings class in .NET
[^]

MCAD

Re: Tutorial on writing and reading configuration file

Fredy27-Aug-05 10:58

Fredy

27-Aug-05 10:58

Thanks alot! This helps.

Have a nice weekend! Wink | ;)

;)

Encryption/Decryption

just4ulove727-Aug-05 7:16

just4ulove7

27-Aug-05 7:16

Hi,
I want to encrypt a password and store the encrypted version in the database. then when the user logs in, I want to decrypt the user password and match with the entered password. I read about DESCryptoServiceProvider, but still i am not able to understand it. Can someone send a link of article which is easy to understand/provide a piece of code here. It would be great for me.

Thanks

Re: Encryption/Decryption

Dave Shaw27-Aug-05 8:33

Dave Shaw

27-Aug-05 8:33

Hi,

If you want to store a password in database, I suggest you use a 'One-Way Hash' algorythm.

These are un-reversable encryption algorythms, hence the name one-way. Then you follow these steps to authenticate your users:

1. User Registers, Username and Hashed Password are stored in DB.
2. User types in Username and Password. P = password
3. The Software encrypts the Users Password with a One-Way Hash. P1 = Hash(P)
4. The Software queries the database and finds the password of the user (Storing Hashed in the database). P2 = database_pass
5. If the Hashed Pass in the DB and Hashed Pass the user typed in Match, Allow Login. If P1 == P2 then Login else Fail (remeber P1 = Hash(P))

Try this code to generate a one-way hash of a password.

-------------------------------------------------------------------------------

private Byte[] GetByteArray( String originalString )
{
Char[] charArray = originalString.ToCharArray();
Byte[] byteArray = new Byte[charArray.Length];
for ( int i=0; i<byteArray.Length; i++ )
{
byteArray[i] = Convert.ToByte( charArray[ i ] );
}
return byteArray;
}

/// <summary>
/// Creates a one-way SHA1 hash of the pt string
/// </summary>
/// <param name="pt">Plaintext to Hash</param>
/// <returns>Ciphertext string</returns>
public string Hash(string pt)
{
//Implement SHA1 Hashing Algorythm (40 Bytes / 320 bits)
byte[] data = new byte[40];
byte[] hash = new byte[40];

while (pt.Length % 4 != 0) pt += "g";

data = Convert.FromBase64String(pt);

SHA1 sha = new SHA1CryptoServiceProvider();
hash = sha.ComputeHash(data);

return Convert.ToBase64String(hash);
}

-------------------------------------------------------------------------------

Thanx!

Dave Shaw

History admires the wise, but elevates the brave. - Edmund Morris

Re: Encryption/Decryption

just4ulove727-Aug-05 8:37

just4ulove7

27-Aug-05 8:37

Thanks a lot Smile | :)

Dynamicaly moving controls at runtime

Mutty27-Aug-05 6:13

Mutty

27-Aug-05 6:13

Hi - I'd like to dynamicaly move a button during runtime.

I've tried changing the control's Control.Location.X and .Y but get the error:
Cannot modify the return value of 'System.Windows.Forms.Control.Location' because it is not a variable.

Is there a way to move a control at run time?

Thanks, mutty

Re: Dynamicaly moving controls at runtime

[Marc]27-Aug-05 6:18

[Marc]

27-Aug-05 6:18

How about Control.Left or control.Top?

Pompiedompiedom... Wink | ;)

"..Commit yourself to quality from day one..it's better to do nothing at all than to do something badly.."
-- Mark McCormick

Re: Dynamicaly moving controls at runtime

Mutty27-Aug-05 6:49

Mutty

27-Aug-05 6:49

So easy... Thanks!

Re: Dynamicaly moving controls at runtime

gnjunge27-Aug-05 7:54

gnjunge

27-Aug-05 7:54

Well and if you want to know why you cannot change it: open reflector and see that the Location property returns the following:

return new Point(this.x, this.y);

So it is returning a new point object. If you anyway want to change the location of the control using the Location property you should feed it a new Point :

Control.Location = new Point(X,Y);

regards,
Gidon

Find Windows version remotely

notacake27-Aug-05 4:06

notacake

27-Aug-05 4:06

Is there a way to find out the Windows version of a machine on the network in C#? I just want the Windows version (9x, XP, etc) and which service pack.

Re: Find Windows version remotely

Matt Gerrans27-Aug-05 7:02

Matt Gerrans

27-Aug-05 7:02

Take a look at WMI -- you can access it with script (VBScript, JScript, Python, Ruby, etc.) or even directly from C# with a little interop. Check out Scriptomatic[^] and look around that same vicinity of TechNet for more WMI information.

Matt Gerrans

what differences came from 'component' and 'windows form'?

Sasuko27-Aug-05 2:49

Sasuko

27-Aug-05 2:49

i need to create a 'window dialog' in .showdialog() for user data input.
i can made it using window form or a component, but i've to do a choose.
What is better?

Line Count and Byte Count

Mridang Agarwalla27-Aug-05 2:45

Mridang Agarwalla

27-Aug-05 2:45

How can i count the number of lines in a string also the number of bytes in a string?

Re: Line Count and Byte Count

FalkoD27-Aug-05 3:22

FalkoD

27-Aug-05 3:22

The number of lines in a string is the number of occurrences of Environment.NewLine + 1. As the string class does not contain a method to count substrings you would probably have to run a for-loop over each char in the string and count.
The number of bytes of a string should be string.Length * sizeof(char).

Re: Line Count and Byte Count

Mohamad Al Husseiny27-Aug-05 3:39

Mohamad Al Husseiny

27-Aug-05 3:39

To Count line in string

Regex rx=new Regex(Environment.NewLine);
MatchCollection mc=rx.Matches(textBox1.Text);
int lineCount=mc.Count;

Note:if the last two chars of string is not Environment.Newline
the line count will be decreased by 1 so you can check
that last two chars in the string is Environment.NewLine
If not add it
To Get the bytes in string use Encoding class
and select Encoding Format you work with
For Example

int cb=Encoding.UTF8.GetByteCount(textBox1.Text);

MCAD

-- modified at 9:40 Saturday 27th August, 2005

Re: Line Count and Byte Count

Lord Kixdemp27-Aug-05 12:58

Lord Kixdemp

27-Aug-05 12:58

Just to make publicity... :-P
Some files can be Mac and Linux files, and they can have different "NewLines"... Look at this program I made, get the source code if you want! Big Grin | :-D

http://www.sulfurmidis.com/sulfursoft/software/tfc.html[^]

Darth_Sulfur (Sulfurik)
http://www.sulfurmidis.com
http://www.sulfursoft.tk
ftp://tsfc.ath.cx
http://tsfc.ath.cx
hotline://tsfc.ath.cx

Re: Line Count and Byte Count

Guffa27-Aug-05 5:28

Guffa

27-Aug-05 5:28

The easiest way of counting the number of line breaks would be to remove them from the string and then check the difference in size:

lines = 1 + ((Len(text) - Len(text.Replace(Environment.NewLine, string.Empty))) / Len(Environment.NewLine));

---
b { font-weight: normal; }

-- modified at 11:28 Saturday 27th August, 2005

Re: Line Count and Byte Count

Rei Miyasaka29-Aug-05 13:04

Rei Miyasaka

29-Aug-05 13:04

To read the number of bytes, you can use Systm.Text.Encoding.Default.GetByteCount.
The most accurate way to count lines would probably be to use StringReader.ReadLine, but if that's too much overhead, try this function:

static int LineCount(string str)
{
	int lines = 1;
	for(int i = 0; i < str.Length; i++)
	{
		if(str[i] == '\r' || str[i] == '\n')
		{
			if(i+1 < str.Length && (str[i] == '\r' && str[i+1] == '\n'))
				i++;
			lines++;
		}
	}
	return lines;
}

-- modified at 19:13 Monday 29th August, 2005

C# and Excel

surfman1927-Aug-05 0:39

surfman19

27-Aug-05 0:39

hi,
how can i read information from a excel table...for example i want to read the row A1 and to write another value back....
any idea to do that?
bye

Re: C# and Excel

Mohamad Al Husseiny27-Aug-05 1:27

Mohamad Al Husseiny

27-Aug-05 1:27

First You need to set reference to Excel Objects Library
One of the class in this library is Worksheet
You can use it to access cells,rows and columns
for example to access the seconed row
Worksheet.Rows(2);
look at
How to Open and Read an Excel Spreadsheet into a ListView in .NET[^]

MCAD

Re: C# and Excel

surfman1927-Aug-05 1:44

surfman19

27-Aug-05 1:44

hi, i compiled this sample!

and i got that error:
private Excel.Application ExcelObj = null;
error CS0246: The type or namespace name 'Excel' could not be found (are you missing a using directive or an assembly reference?)

but the Interop.Excel Assembly = icrosoft Excel 11.0 Object Library is in the projekt!! hmmm...

cu

Connecting application with certain filetype

Member 213090427-Aug-05 0:18

Member 2130904

27-Aug-05 0:18

I've made a little application for opening pictures using pictureboxes. I've used File Type Editor to connect my app with .bmp. .jpg, . gif etc. file types. After instalation, when I doubleclick a picture file, my app runs, but there is no picture in pictureBox1. I know I have to do something with Arguments property, but I dont know what. I've tried:

public static void Main(string[] args)
{
    Application.Run(new Form1());
    args=Environment.GetCommandLineArgs();
    foreach (string arg in args)
    {
      fajl=fajl+arg;
    }
    pictureBox1.Image=Image.FromFile(fajl);

}

How to make doubleclicked file apear in pictureBox1?? Confused | :confused:

please help! Frown | :(

Re: Connecting application with certain filetype

beatles169227-Aug-05 3:03

beatles1692

27-Aug-05 3:03

The line after Application.Run(new Form1()); will not be executed untill you close the form.You should put your code either in Form1 constructor or in form_load event handler or in form_activate event handler

for example:

public static void Main(string[] args)
{
Application.Run(new Form1(args));
}

private Form1(string[] args)
{
foreach(string arg in args)
fajl+=arg;
pictureBox1.Image=Image.FromFile(fajl);
}

P.S. remember that Form1 constructor is an instance member (not a classifier) then none of the variables within it can be static or you should use Form1.variableName to refer to them.

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