C# Discussion Boards - CodeProject

Re: AsyncCallback

_Erik_3-Jun-09 5:25

_Erik_

3-Jun-09 5:25

Hi,

You can try a Mutex

Barcode scanning

KIDYA3-Jun-09 1:56

KIDYA

3-Jun-09 1:56

hello experts

I have scanner thr' which i am scanning barcode.I want to do coding for same.when device trigger clicked,textbox must show respective barcode no.
Give me any useful link or code for same.

Re: Barcode scanning

J4amieC3-Jun-09 2:03

J4amieC

3-Jun-09 2:03

Barcode scanners generally come with an API, or mimic keyboard entry depending on the make/model. There is no way whatsoever for anyone to answer your question without knowing which type of scanner you are using.

KIDYA wrote:
Give me any useful link or code for same.

Even if you had worded that sentence politely (ie, with the addition of the word please) nobody is going to help you unless you help yourself.

Re: Barcode scanning

KIDYA3-Jun-09 2:24

KIDYA

3-Jun-09 2:24

Then what is my work? i m new wid this.is there any operations want to do wid API? or it will installed automatically when set up of scanner install.

Re: Barcode scanning

J4amieC3-Jun-09 2:59

J4amieC

3-Jun-09 2:59

That sentence makes no sense. "wid" is not a word in the English language (Although freakishly enough its my wife's pet name for her dad WTF | :WTF:

dont ask!)

Re: Barcode scanning

EliottA3-Jun-09 3:35

EliottA

3-Jun-09 3:35

Apparently, wid is the new with. Just like his name is the new word for fail.

Check out the CodeProject forum Guidelines[^]

Re: Barcode scanning

Ennis Ray Lynch, Jr.3-Jun-09 2:04

Ennis Ray Lynch, Jr.

3-Jun-09 2:04

Set the focus to your text box and pull the trigger.

Need custom software developed? I do C# development and consulting all over the United States.

A man said to the universe:
"Sir I exist!"
"However," replied the universe,
"The fact has not created in me
A sense of obligation."
--Stephen Crane

Re: Barcode scanning

Luc Pattyn3-Jun-09 3:38

Luc Pattyn

3-Jun-09 3:38

Ennis Ray Lynch, Jr. wrote:
pull the trigger.

stick'em up

Smile | :)

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convert C struct into C#.net

eyeshield213-Jun-09 1:38

eyeshield21

3-Jun-09 1:38

hi,

I want to ask how to convert this C struct into C#.net

typedef struct _MT_EVENT {
#if _WIN32
LARGE_INTEGER TimeStamp; // In FILETIME format
#elif LINUX
struct timeval TimeStamp; // In gettimeofday() format
#endif
ULONG UserStatus; // Not used by API
ULONG EventCode; // Event Code
ULONG SubReason; // Event sub-reason
ULONG XtraInfo; // Extra information, e.g. termination
ULONG FuncCode; // Function active when this event occurred
USHORT Board; // Board ID
USHORT Channel; // Global Channel ID (GCI)
PVOID ptrBuffer; // Related play/record buffer pointer
ULONG DataLength; // Byte length of data accessed (played/recorded)

PVOID ptrXtraBuffer; // Pointer to xtra buffer
ULONG XtraBufferLength; // Length of buffer pointed by ptrXtraBuffer
ULONG XtraDataLength; // Length of data in buffer pointed by ptrXtraBuffer
ULONG EventFlag; // Falgs of the following:
// bit 0x00000001: 1 - Appl created the event
// 0 - NTi DLL created the event
// bit 0x00000002: 1 - Appl allocated ptrtraBuffer
// 0 - NTi DLL allocated ptrXtraBuffer
} MT_EVENT, *PMT_EVENT;

Re: convert C struct into C#.net

Ennis Ray Lynch, Jr.3-Jun-09 2:42

Ennis Ray Lynch, Jr.

3-Jun-09 2:42

Check out the code MS provides for the Windows Mobile Gps, http://msdn.microsoft.com/en-us/library/ms881362.aspx[^] (Sample code comes with the SDK)

It contains many C structs written in C#, fairly cool. (Although, the sample like all MS samples doesn't work out of the box)

Re: convert C struct into C#.net

Rob Philpott3-Jun-09 2:53

Rob Philpott

3-Jun-09 2:53

I'm not so hot on all that interop stuff and its a guess, but you could try this:

[StructLayout(LayoutKind.Sequential)]
public struct _MT_EVENT
{
	public long TimeStamp;
	public ulong UserStatus; // Not used by API
	public ulong EventCode; // Event Code
	public ulong SubReason; // Event sub-reason
	public ulong XtraInfo; // Extra information, e.g. termination
	public ulong FuncCode; // Function active when this event occurred
	public ushort Board; // Board ID
	public ushort Channel; // Global Channel ID (GCI)
	public IntPtr ptrBuffer; // Related play/record buffer pointer
	public ulong DataLength; // Byte length of data accessed (played/recorded)
	public IntPtr ptrXtraBuffer; // Pointer to xtra buffer
	public ulong XtraBufferLength; // Length of buffer pointed by ptrXtraBuffer
	public ulong XtraDataLength; // Length of data in buffer pointed by ptrXtraBuffer
	public ulong EventFlag; // Falgs of the following:
}

Regards,
Rob Philpott.

Re: convert C struct into C#.net

Luc Pattyn3-Jun-09 3:41

Luc Pattyn

3-Jun-09 3:41

size warning: in.NET long/ulong are 64-bit integers, in most other languages when targettingt a 32-bit CPU they just take 32-bit.

http://www.pinvoke.net[^] holds lots of useful interop stuff, however it also contains some mistakes, frequently passing a pointer as int (should be IntPtr).

Smile | :)

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Show formatted code inside PRE tags, and give clear symptoms when describing a problem.

Re: convert C struct into C#.net

Ennis Ray Lynch, Jr.3-Jun-09 5:16

Ennis Ray Lynch, Jr.

3-Jun-09 5:16

That is the primary reason I encourage (require) programmers on my teams not to use int and long in C# and instead require Int32 and Int64. The same issue comes up a lot in database programming. I am absolutely sick and tired of seeing cast errors in code because a programmer doesn't know what type they are using.

Re: convert C struct into C#.net

eyeshield213-Jun-09 18:40

eyeshield21

3-Jun-09 18:40

thanks alot all...

How to convert a string to double with out lossing precission??

prathapcode3-Jun-09 1:23

prathapcode

3-Jun-09 1:23

Hi,

I have a string with value "111733394601234567094987654321" . Now i want to divide this with 636. I convert it to double , then im getting 1.1173339460123456E+29 . but these both values are differnt finally im
getting wrong output. can anyone help me.....

Thanks
Prathap

Re: How to convert a string to double with out lossing precission??

Moreno Airoldi3-Jun-09 1:29

Moreno Airoldi

3-Jun-09 1:29

There is no way you can do that with doubles. Since the value is too big even for a 64 bit integer, you should use some 128-bit integer class. See for example this[^] or Google for some more.

2+2=5 for very large amounts of 2
(always loved that one hehe!)

Re: How to convert a string to double with out lossing precission??

Luc Pattyn3-Jun-09 3:45

Luc Pattyn

3-Jun-09 3:45

The latest .NET 4.0 (and Visual Studio 2010) is in beta and offers a BitInteger class which would easily take care of your big integer division, yielding accurate quotient and remainder values.

There also have been some articles on home-brew BigInteger classes here on CP (with varying functionality and quality).

Smile | :)

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.

& missing

benjamin yap3-Jun-09 1:12

benjamin yap

3-Jun-09 1:12

Hi, my database has a column called 'course'. I have a value "Game & Entertainment Technology"

when i extract the value using

acc.Course = reader.GetValue(4).ToString();<br />
lblCourse.Text += " " + acc.Course.ToString();

the value becomes Game Entertainment Technology.. the & disappear

Re: & missing

Rob Philpott3-Jun-09 1:21

Rob Philpott

3-Jun-09 1:21

That's because & is used to underline a letter for a shortcut. You need to double it to &&.

acc.Course = reader.GetValue(4).ToString();
lblCourse.Text += " " + acc.Course.ToString().Replace("&", "&&");

Regards,
Rob Philpott.

Re: & missing

Rob Philpott3-Jun-09 1:24

Rob Philpott

3-Jun-09 1:24

Actually, presuming reader is a SqlDataReader and acc.Course is a string you can shorten this to:

acc.Course = reader.GetString(4);
lblCourse.Text += " " + acc.Course.Replace("&", "&&");

Regards,
Rob Philpott.

Re: & missing

benjamin yap3-Jun-09 1:26

benjamin yap

3-Jun-09 1:26

thanks alot!

1 more question. My first screen is a login screen. Therefore i have a username and password textbox.

private void btnLogin_Click_1(object sender, EventArgs e)<br />
{<br />
    bool validate = db.authenticate(tbxUsername.Text, tbxPassword.Text);<br />
    if (!validate)<br />
    {<br />
        MessageBox.Show("Invalid Credentials");<br />
    }<br />
    else<br />
    {<br />
        frmMain main = new frmMain(tbxUsername.Text);<br />
        <br />
        main.Show();<br />
        this.Hide();<br />
        <br />
    }<br />
}

Is it possible to close the login form instead of hiding it? I do a this.close() but after i login everything close.

Also, my db.authenticate is not case sensitive. The password in the database is 'test'. However when i entered 'TEST', it works too.

Re: & missing

Henry Minute3-Jun-09 1:33

Henry Minute

3-Jun-09 1:33

If the login form is the first one created and called from Program.cs, the application classes it as the 'Main' form of the application. When the main form closes, the application closes.

There are loads of examples of using a login form on the web, have a quick google to see how to do it.

Henry Minute

Do not read medical books! You could die of a misprint. - Mark Twain
Girl: (staring) "Why do you need an icy cucumber?"
“I want to report a fraud. The government is lying to us all.”

Re: & missing

benjamin yap3-Jun-09 1:38

benjamin yap

3-Jun-09 1:38

Okay. Noted. Thanks

What bout make the password and username case sensitive?

Re: & missing

Henry Minute3-Jun-09 2:03

Henry Minute

3-Jun-09 2:03

You stated that db.authenticate was not case sensitive. I can not find any reference to an authenticate method for any database related classes, so I assume that it is one you have written yourself.
If that is so, take a look at this[^].

I not, I am unable to help.

Re: & missing

benjamin yap3-Jun-09 3:52

benjamin yap

3-Jun-09 3:52

thanks. i found the solution.

inside phpmyadmin, i change the collation to latin1_general_cs.

cs refers to case sensitive

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