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1.
mprice214 wrote:
RxString.Remove(0, 3); //This removes the first 4 characters
Not true. At best it removes 3 characters; and if there are fewer, expect an exception.
Yes, understand. I originally was removing 4.
2.
mprice214 wrote:
double.Parse (RxString);
that will fail if the data isn't really a string representation of a double. Don't do this on external data, it will bite you. Either add try-catch or better yet use TryParse().
Understand this too
3.
why does DisplayText() have parameters which make it look like a real event handler, you are not using those parameters, instead you are using some class member. It would seem logical to give it one parameter: the text it should display.
see #6
4.
mprice214 wrote:
serialPort1.WriteLine("*X01\r");
very strange. You want a carriage return plus whatever the system uses for a newline (maybe "\r\n"). Either you like what the system gives you, or you don't; I would never mix the two.
The device only requires a cr and as result, it is fine with just \r or \r and \n. Why would a newline be necessary here?
5.
mprice214 wrote:
catch (Exception Exception)
{
return;
}
This is not acceptable; whatever goes wrong, you ignore it. So when it goes wrong, you will have an impossible job to diagnose and fix the problem. And believe me, serial communication always goes wrong sooner or later. You should NOT swallow exceptions, either catch a very specific one and add a comment as to why you really don't care about it, or log it somewhere so it leaves a trail.
Understand. I am trying to get things working first and then am going back to clean up. As I'm relatively new to c#, I'm sure I'll miss some things.
6.
mprice214 wrote:
this.Invoke(new EventHandler(DisplayText));
That does not work, as the parameter list does not match. First make sure which parameters the method should have, then make sure to provide them, using an overload of Invoke().
When I run this, it works. Correct me if I am wrong, but doesn't this pass RxSring back to DisplayText? Are you saying there is a better way to do this?
Regarding the initial question, I need to pass RxString out of DisplayText as a double to use for graphing purposes.
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mprice214 wrote: The device only requires a cr
so use serialPort1.Write("*X01\r"); instead of WriteLine() and you're in charge, now it doesn't matter what SerialPort.NewLine contains any more.
mprice214 wrote: get things working first
sure, so am I. By seeing exceptions right away. As a minimum, add Console.WriteLine(exception.ToString());. Either you don't have exceptions, then it makes no difference; or you have, and now you can see them.
mprice214 wrote: it works
Yes, I forgot: Invoke without parameters provides some defaults, and since you don't really use the parameters inside DisplayText, there is no problem. However, I wouldn't do it like that.
mprice214 wrote: Regarding the initial question
OK, if you are not really interested in the string, why not use a class member "double Rx;" instead of "string RxString;". Have DataReceived read the string, convert it to double, and store the value in Rx; then have DisplayText and any other interested method just read the Rx variable.
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Luc Pattyn wrote: Yes, I forgot: Invoke without parameters provides some defaults, and since you don't really use the parameters inside DisplayText, there is no problem. However, I wouldn't do it like that.
Do you have any other suggestions?
Luc Pattyn wrote: OK, if you are not really interested in the string, why not use a class member "double Rx;" instead of "string RxString;". Have DataReceived read the string, convert it to double, and store the value in Rx; then have DisplayText and any other interested method just read the Rx variable.
Thank you for this and also the the comment on the exceptions!
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you're welcome.
mprice214 wrote: any other suggestions?
yes, if you need parameters, use the Invoke() overload that takes an array of objects.
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mprice214 wrote: this.Invoke(new EventHandler(DisplayText));
Has some paramter issues, to get around it without changing too much code try this
this.Invoke(new MethodInvoker(delegate{DisplayText(null, null);}));
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I'm not sure why this would need to change, as it seems to work fine. I'm apparently missing something here. BTW, RxString is global.
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I need help. I want to save the datatable to a *.xls file. wBook.FileFormat is only get Attribute.
How to set the file type to *.xls?
<code>
Excel.Application app = new Microsoft.Office.Interop.Excel.ApplicationClass();
try
{
app.Visible = false;
Excel.Workbook wBook = app.Workbooks.Add(true);
Excel.Worksheet wSheet = wBook.Worksheets[1] as Excel.Worksheet;
if (dt.Rows.Count > 0)
{
int row = 0;
row = dt.Rows.Count;
int col = dt.Columns.Count;
for (int i = 0; i < row; i++)
{
for (int j = 0; j < col; j++)
{
string str = dt.Rows[i][j].ToString();
wSheet.Cells[i + 2, j + 1] = str;
}
}
}
int size = dt.Columns.Count;
for (int i = 0; i < size; i++)
{
wSheet.Cells[1, 1 + i] = dt.Columns[i].ColumnName;
}
app.DisplayAlerts = false;
app.AlertBeforeOverwriting = false;
wBook.Save();
app.Save(filePath);
app.SaveWorkspace(filePath);
app.Quit();
app = null;
}
catch (Exception err)
{
return -1;
}
finally
{
}
</code>
modified on Friday, April 16, 2010 8:07 AM
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so you are trying to save in *.xls format from C# by using Interop. But you have excel 2007 wright?
If that's the case a little trick:
record a macro that stores the save as 2003
ActiveWorkbook.SaveAs Filename:= _
"C:\Users\dan.mos\Desktop\New Microsoft Office Excel Worksheet (2).xls", _
FileFormat:=xlExcel8, Password:="", WriteResPassword:="", _
ReadOnlyRecommended:=False, CreateBackup:=False
and convert it to c# code. It works like a charm.
As a sugestion your cell by cell approach is really slow especially for large amounts of data.
Have a look here or
here.
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Hi guys,
I have a datagrid that includes a checkbox in each row...
Does anyone know how I can check which rows have a checked check box?
and retrieve a certain value(say mobile number)
Please help 
Here is what i have tried:
CheckBox chkSelection;
foreach (DataGridItem item in contacts.Items)
{
chkSelection = (CheckBox)item.FindControl("chkSelection");
if (chkSelection.Checked == true)
{
Control contact = (Control)item.FindControl("phone_num");
errors0.Text += contact.ToString();
errors0.Visible = true;
}
}
No this won't work
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Hi dear,
please specify what errors0 means. well try one thing change the datatype I suppose phone_num is a text box so cast it to textbox and then try to have its value using tostring.
<br />
if (chkSelection.Checked == true) { <br />
TextBox contact = (TextBox)item.FindControl("phone_num");<br />
errors0.Text += contact.ToString(); <br />
errors0.Visible = true;
}<br />
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Hi there thanks for my reply.
well, phone_nume is a column in the datagride that holds phone numbers
and chkSelection is a checkbox id that is in the same datagrid.
I would like to retrieve these phone numbers where a checked is = true...
Do you know how you can do this?
Oops! errors0 is just a demo Label to display the numbers after retrieving them
from my datagrid..
Please help if you can...
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Hi,
I develop a Csharp smart device application.I was in the first step.I create a ConnexionForm where user writes his login and password,the system verifys if they are in the database .sdf.I write this code:
private void button1_Click(object sender, EventArgs e)
{
string s1 = textBox1.Text.ToString();
string s2 = textBox2.Text.ToString();
BaseGmaoLocaleDataSet2 dat = new BaseGmaoLocaleDataSet2();
DataRow[] foundRows;
foundRows = dat.Tables["Connexion"].Select("Login like s1 and MotPasse like s2");
if (foundRows != null)
{
MessageBox.Show("Authentification réussie");
MenuP m = new MenuP();
m.Show();
}
else
{
MessageBox.Show("Login ou mot de passe incorrect veuillez réessayer");
}
}}}
But an error appears to me telling me that there is an error in the form of the 2 strings s1 et S2
Can you help me?
Thanks for all u suggestions
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Hi,
several comments:
1.
your database does not know what s1 and s2 mean in Select("Login like s1 and MotPasse like s2");
you want the content of s1 and s2, not the names of the variables; so they must not be inside double quotes.
and then you want SQL to see them as string literals, which requires single quotes.
So at least you should change it to
...Select("Login like '"+s1+"' and MotPasse like '"+s2+"'");
2.
it does not make sense to use like like that, there are no wildcards, nor anything special. So better write
...Select("Login = '"+s1+"' and MotPasse = '"+s2+"'");
3.
you should not pass user input straight to an SQL statement, it makes your app very vulnerable; the user could type things that end up your SQL statement do things you don't want such as delete a table.
Either check your inputs (you must avoid empty fields too!) or use parameterized SQL (use SQLParameter).
4.
You should not store plain passwords in a database; you should use encryption or hashing. Read up on best practices for passwords!
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I would try putting the s1 and s2 into single quotes and maybe using wild cards (%)
foundRows = dat.Tables["Connexion"].Select("Login like '%" + s1 + "%' and MotPasse like '%" + s2 +"%'");
Lucs answer is better. See that.
modified on Tuesday, April 13, 2010 9:06 AM
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it should work, however I don't think wildcards are a good idea for authentication.
Chances are entering
username: a
password: a
will let you in, as it would match Jan/MySecretPassword as well as an infinite number of other possible accounts.
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Hi,
Thank u Lucs,the error desappears but a new problem appears:
althougth the login and password are not in my database .sdf,the system returns"successful authentification".
What should I add to correct this??
Thanks a lot for u contribution
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string s1 = textBox1.Text.ToString();
string s2 = textBox2.Text.ToString();
Text property is already a string, so you don't need the ToString() method here. So :
string s1 = textBox1.Text;
string s2 = textBox2.Text;
is sufficient.
SqlCeConnection cnx = new SqlCeConnection("...");
string req = "SELECT * FROM Connexion WHERE Login = @login AND MotPasse = @pass";
SqlCeCommand cmd = new SqlCeCommand(req, cnx);
SqlCeParameter login = new SqlCeParameter("login", s1);
cmd.Parameters.Add(login);
SqlCeParameter pass = new SqlCeParameter("pass", s2);
cmd.Parameters.Add(pass);
...
Here's the general idea. Hope it'll be useful.
modified on Tuesday, April 13, 2010 10:54 AM
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O.Phil wrote: textBox1.Text.ToString()
or textBox1.Text.ToString().ToString()
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I was just observing that "Text property is already a string, so you don't need the ToString() method here." 
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right.
And a good thing about TextBox is it's Text property never returns null.
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Hi,
I add what u tell me about but still the same problem.
private void button1_Click(object sender, EventArgs e)
{
string s1 = textBox1.Text;
string s2 = textBox2.Text;
SqlCeConnection cnx = new SqlCeConnection();
string wCS = String.Format("DATA SOURCE = '{0}';", Program.gFichierBase);
cnx.ConnectionString = wCS;
string req = "SELECT * FROM Connexion WHERE Login = @login AND MotPasse = @pass";
SqlCeCommand cmd = new SqlCeCommand(req, cnx);
SqlCeParameter login = new SqlCeParameter("login", s1);
cmd.Parameters.Add(login);
SqlCeParameter pass = new SqlCeParameter("pass", s2);
cmd.Parameters.Add(pass);
BaseGmaoLocaleDataSet2 dat = new BaseGmaoLocaleDataSet2();
DataRow[] foundRows;
foundRows = dat.Tables["Connexion"].Select("Login like '%" + s1 + "%' and MotPasse like '%" + s2 + "%'");
if (foundRows != null)
{
MessageBox.Show("Authentification réussie");
MenuP m = new MenuP();
m.Show();
}
else
{
MessageBox.Show("Login ou mot de passe incorrect veuillez réessayer");
}
}
It seems so difficult
Thanks for u contribution
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Hi,
When you use the SqlCe Connection and Command object, you don't need to use your dataset anymore.
If you have MSDN installed, you can check the use of these objects (particularly the SqlCeCommand object, since this is the one that actually does the request).
So :
{...}
cmd.Parameters.Add(pass);
int count = cmd.ExecuteScalar();
if (count == 1)
{
MessageBox.Show("Authentification réussie");
MenuP m = new MenuP();
m.Show();
}
else
MessageBox.Show("Login ou mot de passe incorrect veuillez réessayer");
Here's the idea. Courage !
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Use Scope_Identity instead. It's the recommended option.
"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.
My blog | My articles | MoXAML PowerToys | Onyx
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from msdn
IDENT_CURRENT is similar to the SQL Server 2000 identity functions SCOPE_IDENTITY and @@IDENTITY. All three functions return last-generated identity values. However, the scope and session on which last is defined in each of these functions differ:
* IDENT_CURRENT returns the last identity value generated for a specific table in any session and any scope.
* @@IDENTITY returns the last identity value generated for any table in the current session, across all scopes.
* SCOPE_IDENTITY returns the last identity value generated for any table in the current session and the current scope.
So SCOPE_IDENTITY seems the right one in a multi threaded environment.
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