C# Discussion Boards - CodeProject

23-Jul-09 23:33

Hello,
i was trying to simplify my code but i have a problem with the code here:

public void Send(byte a, byte b, byte c)
     {
         byte[] ab = new byte[3];
         ab[0] = a;
         ab[1] = b;
         ab[2] = c;
         ab[3] = a ^ b ^ c;
         serialPort1.Open();
         serialPort1.Write(ab, 0, 3);
         serialPort1.Close();
     }

When is use this code there is an error in this line:

ab[3] = a ^ b ^ c;

the error is:
Error 1 Cannot implicitly convert type 'int' to 'byte'. An explicit conversion exists (are you missing a cast?) C:\Users\***\AppData\Local\Temporary Projects\WindowsFormsApplication1\Form1.cs 27 21 WindowsFormsApplication1

Is there some one that can help me?

DaveyM6923-Jul-09 23:39

DaveyM69

23-Jul-09 23:39

Whenever you use the xor operator (^) (and any of the other operators to) it treats everything as an int Mad | :mad:

.
Change it to

ab[3] = (byte)(a ^ b ^ c);

Dave
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Member 474292223-Jul-09 23:41

23-Jul-09 23:41

Thank you for your fast reply it solved my problem! thank you very much!

Muhammad Mazhar23-Jul-09 23:45

Muhammad Mazhar

23-Jul-09 23:45

sounds like the resultant value produced is out side byte range and hence overflow that's why its asking for explicit conversion. Make sure the values you passing for a,b and c produce a value within byte range.

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Member 474292223-Jul-09 23:52

23-Jul-09 23:52

it does, because its sending the result to my serialport, so the value is never bigger then 255.
Thanks for your help!;)

harold aptroot24-Jul-09 4:06

harold aptroot

24-Jul-09 4:06

How exactly would a xor overflow?

musefan24-Jul-09 0:03

24-Jul-09 0:03

byte[] ab = new byte[3];
ab[0] = a;
ab[1] = b;
ab[2] = c;
ab[3] = (byte)(a ^ b ^ c);

Warning: "index out of bounds" is imminent

Life goes very fast. Tomorrow, today is already yesterday.

Member 474292224-Jul-09 1:14

24-Jul-09 1:14

I know that but thank you for the anouncement;) im very happy that you guys helped me out!

0x3c024-Jul-09 0:39

0x3c0

24-Jul-09 0:39

Following on to musefan's point, you have a subtle error in your declaration of the byte array. In this line:

byte[] ab = new byte[3]

You declare ab as a byte array which can only hold three elements. However, in the lines below it, you fill it with four elements; as has been said, this will cause an IndexOutOfRangeException (or something like that) when you assign a value to ab[3]. To fix this problem, change the declaration of ab to

byte[] ab = new byte[4]

This will allow ab to hold four elements, fixing the error

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How to make a Component like MSN status label?

Luc Pattyn24-Jul-09 0:49

Luc Pattyn

24-Jul-09 0:49

Hi,

this is what I would write:

List<byte> list=new List<byte>();
list.Add(a);
list.Add(b);
list.Add(c);
writeWithXor(port, list);
...
public void writeWithXor(SerialPort port, List<byte>list) {
    int xor=0;
    foreach(byte b in list) xor^=b;
    list.Add((byte)xor);
    port.Write(list.ToArray());
    list.Clear();
}

This way you don't have the hassle of counting bytes and allocating the right array; and you can reuse
writeWithXor() for any amount of data that needs to be followed by a 'checksum'; and of course I would keep the serial port open, probably as long as my app is running.

Smile | :)

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Don.Y23-Jul-09 23:19

Don.Y

23-Jul-09 23:19

I want 2 create a component like msn status lable.
that look like a label & a textbox & a dropDownList.

it can drop down show the menu,and it can be edited when I click the label.

how to do that?

Re: How to make a Component like MSN status label?

DaveyM6923-Jul-09 23:21

DaveyM69

23-Jul-09 23:21

You make a user control with a Label, TextBox and ComboBox

Re: How to make a Component like MSN status label?

Muhammad Mazhar23-Jul-09 23:38

Muhammad Mazhar

23-Jul-09 23:38

Most probably you will make a user control.

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Re: How to make a Component like MSN status label?

Tamer Oz24-Jul-09 0:21

Tamer Oz

24-Jul-09 0:21

Develop an user control or a composite control.

http://msdn.microsoft.com/en-us/library/aa719968(VS.71).aspx[^] can give you some idea

a strange problem with windows service

saeidfarahi23-Jul-09 22:53

saeidfarahi

23-Jul-09 22:53

this question is a mixture of sql and c# windows services...
i have a windows service which connects to COM1 port(serial port) and writes the data into a sql db. i have an installer which installs the service and run it immidiatly after setup is completed , but stops very soon because of this error which appears in event log :
provide : named pipes provider . error 40 - could not connect to sql server
i have installed sql server 2005 (not express ed) and the connection string
in my service is :
Confused | :confused:

string _connectionstring =
"server=" + Environment.MachineName +";Initial Catalog=myDatabase;"+
"user id=myLogin;password=myPassword;trusted_connection = true;";

i have tested this connection string in a simple windows form and it works!
please notice that this sql server and windows service are working on local computer , not a network. OMG | :OMG:

musefan23-Jul-09 23:17

23-Jul-09 23:17

check that Environment.MachineName is returning the correct value you need, i.e. the SQL Server location. The other information in your connection string should be irrelevant at this time, as with the error you have the issue is usually because is pointing to wrong place

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DoctorMick23-Jul-09 23:38

DoctorMick

23-Jul-09 23:38

I think you may have a conflict in your connection string. You are providing a user name and password but also specifying trusted_connection=true. My assumption is that the service is trying to logon to the SQL server as the user the service is running under. Try changing trusted_connection = true to trusted_connection = false.

musefan23-Jul-09 23:42

23-Jul-09 23:42

Would that not be an authentication error instead thou?

Life goes very fast. Tomorrow, today is already yesterday.

DoctorMick24-Jul-09 0:11

DoctorMick

24-Jul-09 0:11

Quite possibly but I couldn't count the number of error messages I've seen that don't really relate to what the problem is. Laugh | :laugh:

musefan24-Jul-09 0:16