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The .Net documentation for String.Contains() (http://msdn2.microsoft.com/en-us/library/system.string.contains.aspx) says it may raise the System.ArgumentNullException exception. This is the only exception listed for this method.
However, when I use this method to examine the contents of string based object properties, I'm getting the following exception instead:
System.NullReferenceException: Object reference not set to an instance of an object
Note that the exception doesn't happen unless I use the .Contains() method.
For instance, in the following code:
string myString = object.stringProperty;<br />
MessageBox.Show(myString);<br />
<br />
if (myString.Contains("a")) { ... }
no exception is thrown until the "if" statement is executed.
So, is the documentation incorrect, or is there something special about the empty string being held by the object property?
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Have you checked myString to see if it's null or not?
Cyril Connolly wrote: Truth is a river that is always splitting up into arms that reunite. Islanded between the arms, the inhabitants argue for a lifetime as to which is the main river.
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Clearly, I have not  . But I'm not sure what point you are making?
Am I wrong in assuming that the list of Exceptions in the String.Contains() documentation is exclusive and complete?
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It's not a string exception, it's a runtime exception. You're calling a method on a null object.
Cyril Connolly wrote: Truth is a river that is always splitting up into arms that reunite. Islanded between the arms, the inhabitants argue for a lifetime as to which is the main river.
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I guess I'm confused why none of the other code is throwing an exception on the null object. I can pass that object to MessageBox.Show, I can add another string to it, etc. It's only when I call .Contains() that it coughs up a lung...
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However, thanks for your help. I'll guess I'll have to be more defensive in null checking on reference values returned from properties. Dang those inconsiderate objects!
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Are you aware of FxCop[^]? I don't know if it will identify the problem above, but I analyzed a project and FxCop found a couple of instances of not checking if an object was valid before using it.
Cyril Connolly wrote: Truth is a river that is always splitting up into arms that reunite. Islanded between the arms, the inhabitants argue for a lifetime as to which is the main river.
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My application has got 3-4 solution and each solution have few projects in it. Currently all the confiugration data for my application is scattered across various project.config files in individual project.
I want to merge all these configuration settings and make a one single config file which will be accessed by all solutions / projects. If possible I would like to read/write this common file using "Properties.Settings" class as we normally read the config files.
Can any one give me idea on how to achieve the above thing?
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I'm having an issue trying to get my clients to handle messages that are passed from a server to a shared object... Any remoting gurus out there are free to enlighten me... 
Ok.. First of all, here is the interface created to by implemented by the remote object:
namespace WarComInterface<br />
{<br />
<br />
public delegate void ServerToClientEvent(object sender, ServerToClientEventArgs e);<br />
<br />
public interface ICom<br />
{<br />
Joueur clientReqJoueur(string nomJoueur);<br />
<br />
event ServerToClientEvent ServerToClientMsg;<br />
<br />
void clientMsg(EventTypes.EventsFromClient typeEvent, string nomJoueur);<br />
}<br />
}
Now, here is the part where the client gets a reference to the remote object and sets a handler to listen for events coming from the server:
<br />
try<br />
{<br />
TcpChannel channel = new TcpChannel();<br />
ChannelServices.RegisterChannel(channel, false);<br />
remoteComm = (WarComInterface.ICom)Activator.GetObject(typeof(WarComInterface.ICom),<br />
"tcp://"+txt_adrip.Text + ":1069/jh");<br />
<br />
remoteComm.ServerToClientMsg += new ServerToClientEvent(MessageFromServer);<br />
<br />
And finally, this is the part inside the shared object. It's within a public method called by the server (some sort of public void sendMsg())
<br />
evArg = new ServerToClientEventArgs(EventTypes.EventsFromServer.UpdateStats, targetPlayer);<br />
if (ServerToClientMsg != null)<br />
{<br />
ServerToClientMsg(this, evArg); <br />
}<br />
It fires up the following exception : This remoting proxy has no channel sink which means either the server has no registered server channels that are listening, or this application has no suitable client channel to talk to the server.
Any help would be greatly appreciated!
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I've seen that message. For me, it meant that the client was not defining a suitable channel for the event callbacks. What makes yours "unsuitable" might be the absence of a channel altogether (which I doubt, looking at your sample), permissions (which I don't understand), or the absence of the typeFilterLevel attribute for the channel. In the server's config file, the latter would look like:
<serverProviders>
<formatter ref="binary" typeFilterLevel="Full" />
</serverProviders>
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Hello everyone,
How can I get the focus on a Window Form? This is my problem. I have created a Media Player using DirectShow in C# enviroment. When I use the full-screen mode and enlarge the screen after reducing the size to normal, no longer I can have any form open on the TOP of the other windows.
Thank you very much and have a great day,
Khoramdin
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This means your form is topmost. You can change ths property.
Or do you mean forms in your program ? If the form is modal, then it takes the focus and no other form can be accessed.
Christian Graus - Microsoft MVP - C++
"also I don't think "TranslateOneToTwoBillion OneHundredAndFortySevenMillion FourHundredAndEightyThreeThousand SixHundredAndFortySeven()" is a very good choice for a function name" - SpacixOne ( offering help to someone who really needed it ) ( spaces added for the benefit of people running at < 1280x1024 )
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Hello Christian,
Thanx for the reply. You were absolutly correct. I checked the codes and realised where the prroblem was.
Thank you for the help.
Khoramdin
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Is there a way to change a color with a number in code? It's confusing, but I want to set a timer to change 1 of the 3 color parts, and I just need to know how to reach them. Thanks in advance.
The most knowledge doesn't mean the most wise...
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Hi,
try this:
Color color;
...
int red=color.Red+1;
if (red>255) red=255;
int green=color.Green;
int blue=color.Blue-1;
if (blue<0) blue=0;
color=Color.FromArgb(red, green, blue);
Luc Pattyn [Forum Guidelines] [My Articles]
this months tips:
- use PRE tags to preserve formatting when showing multi-line code snippets
- before you ask a question here, search CodeProject, then Google
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Thanks, Luc.
The most knowledge doesn't mean the most wise...
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Hw do I set that to the forms backcolor?
The most knowledge doesn't mean the most wise...
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Hi,
the main thread simply does myForm.BackColor=color;
for animation purposes, I prefer the Windows.Forms.Timer timer; other timers tick
on a different thread and would need Control.InvokeRequired and Control.Invoke()
to touch the Form.
Luc Pattyn [Forum Guidelines] [My Articles]
this months tips:
- use PRE tags to preserve formatting when showing multi-line code snippets
- before you ask a question here, search CodeProject, then Google
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Is there any way to make a method that the form continuously calls on? Or, is there a way to make a method that it calls without you having to call it? Like, Say how Form1_Load gets called on its own, is there a way to do that with a method you make? I hope that didn't come out too confusing, much thanks in advance.
-- modified at 17:00 Wednesday 24th October, 2007
The most knowledge doesn't mean the most wise...
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To create a method that form continuosly calls you have to create a timer object, and initalize it on constructor or form load.
See and example here http://www.csharphelp.com/archives/archive90.html
Visit my blog at http://dotnetforeveryone.blogspot.com
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Thanks.
The most knowledge doesn't mean the most wise...
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Also, for simple timer methods, I like to use anonymous delegates. Like this:
myTimer.Tick += delegate { Invalidate(); };
The invalidate is just the sample code inside the anonymous delegate, you can put anything there.
When you do this, any variables created inside the method that defnes the delegate are in scope, but I like it more because it defines what the timer does at the point that I create it.
Christian Graus - Microsoft MVP - C++
"also I don't think "TranslateOneToTwoBillion OneHundredAndFortySevenMillion FourHundredAndEightyThreeThousand SixHundredAndFortySeven()" is a very good choice for a function name" - SpacixOne ( offering help to someone who really needed it ) ( spaces added for the benefit of people running at < 1280x1024 )
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Hello, I am a beginning C# programming student at a university and I'm having trouble making a previous program of mine modular. We wrote a program that calculated an employee's net pay, and now we have to make it modular by adding 3 methods. I've done just as the examples are in our notes and all I get is an error saying invalid namespace. Here is my original code:
<pre>
using System;
using System.Collections.Generic;
using System.Text;
namespace Program5
{
class Program
{
const double DEPINS = 25.50;
const double TAX = .23;
static void Main()
{
int dep;
double grossPay, hourRate, hourWorked, deduct, netPay, depIns, tax;
Console.Write("Hours Worked: ");
hourWorked = Double.Parse(Console.ReadLine());
Console.Write("Hourly Rate: ");
hourRate = Double.Parse(Console.ReadLine());
Console.Write("Dependents: ");
dep = Int32.Parse(Console.ReadLine());
if (hourWorked >= 40)
grossPay = Math.Round(1.5 * hourRate * hourWorked, 2);
else
grossPay = Math.Round(hourRate * hourWorked, 2);
depIns = dep * DEPINS;
tax = grossPay * TAX;
deduct = Math.Round(depIns + tax, 2);
netPay = grossPay - deduct;
Console.WriteLine("");
Console.WriteLine("Hours Worked: {0,9:n}", hourWorked);
Console.WriteLine("Hourly Rate: {0,9:n}", hourRate);
Console.WriteLine("Dependents: {0,9}", dep);
Console.WriteLine("Gross Pay: {0,9:n}", grossPay);
Console.WriteLine("Deductions: {0,9:n}", deduct);
Console.WriteLine(" ---------");
Console.WriteLine("Net Pay: {0,9:c}", netPay);
}
}
}
</pre>
Thanks!
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If I cut and paste your example code it compiles fine. What are you using to compile the code? Does it say which namespace is invalid? Or a line number?
Take care,
Tom
-----------------------------------------------
Check out my blog at http://tjoe.wordpress.com
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Yeah, it compiles fine because I copy and pasted the original coding without what I put in when I tried to make it modular. What I tried to do looked something like this:
<pre>
using System;
using System.Collections.Generic;
using System.Text;
namespace Program5
{
class Program
{
const double DEPINS = 25.50;
const double TAX = .23;
static void GetData()
{
int dep;
double grossPay, hourRate, hourWorked, deduct, netPay, depIns, tax;
Console.Write("Hours Worked: ");
hourWorked = Double.Parse(Console.ReadLine());
Console.Write("Hourly Rate: ");
hourRate = Double.Parse(Console.ReadLine());
Console.Write("Dependents: ");
dep = Int32.Parse(Console.ReadLine());
}
static void CalcNet()
{
if (hourWorked >= 40)
grossPay = Math.Round(1.5 * hourRate * hourWorked, 2);
else
grossPay = Math.Round(hourRate * hourWorked, 2);
depIns = dep * DEPINS;
tax = grossPay * TAX;
deduct = Math.Round(depIns + tax, 2);
netPay = grossPay - deduct;
}
static void DspData()
{
Console.WriteLine("");
Console.WriteLine("Hours Worked: {0,9:n}", hourWorked);
Console.WriteLine("Hourly Rate: {0,9:n}", hourRate);
Console.WriteLine("Dependents: {0,9}", dep);
Console.WriteLine("Gross Pay: {0,9:n}", grossPay);
Console.WriteLine("Deductions: {0,9:n}", deduct);
Console.WriteLine(" ---------");
Console.WriteLine("Net Pay: {0,9:c}", netPay);
}
static void Main ()
{
GetData();
CalcNet();
DspData();
}
</pre>
So what I did is I set it up exactly like it was set up in an example program from my notes which I copy and pasted and compiled and that worked just fine, but when I do it with this program it says my namespace is invalid and that I need a semi-colon after the static void's which I know is incorrect. So I have no idea what is going on.
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