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Anonymous wrote:
i bound a reference into my program but when i try to start it, an unhandled exception occures: "Object reference not set to an instance of an object"
how can i resolve this?
You need to initialize your object within the application, try adding something like the following, possibly in InitializeComponent().
this.YourObject1 = new YourObject();
Nick Parker
The only man who never makes a mistake is the man who never does anything. - Theodore Roosevelt
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Hello NG,
I have a standard C# Class-library Project and want it to behave like the SQl-Connection User Control. Means you can drag it from the toolbox on a form and it docks underneath the forms designer.
Does anybody know how to achieve this?
Thanks in advance
Stefan
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You should inherit "Component" not "Control"
//Roger
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Thanks for the fast Answer Roger 
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How to Select a existing directory name by showing a dialog.
( like in .net environment : file->newproject->location )
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Take a look at this [^] article written by Rama Krishna
Cheers,
John
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Hi, all, again!
Would you like to help me, plz?
Have the folow:
I want to create COM+ component with help c#, so, it will use the external(usual) dll-file(my.dll), where contents some logic (com-objects).
This dll good work in usual application, when add it as reference - all ok.
(a have not source for this dll file)
But when i try to link up it in my developed com+ app., - got folow answer from compiler:
"Assembly generation failed -- Referenced assembly 'name of my.dll' does not have a strong name"
is it have not 'strong name'????
i try the next:
al /out:my.dll "?" /keyfile:my_dll.snk
but it don't want to work... i do not understand want is this "?"
and is it right way to solve this problem? and what i must do in this case?
in any case thx.
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I am pretty new to C# and the .NET fromework for that matter. I have recently began working on a Binary Tree class and would like to be able to store any type a user wants to store (i.e. Object). I would like to hide the implementation of this class from the user, however I am having trouble discerning what type the data is that is being stored in this class. I would like to be able to do some sort of "dyanmic cast" on the data and call the appropriate CompareTo() method. I would like to not have to always test on the type of the data and then cast the data to that specific type.
Is this possible?
Hope this makes sense!
Any help would be greatly appreciated.
Thanks
Michael
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Look up typeof. It will do what you want.
Christian
No offense, but I don't really want to encourage the creation of another VB developer.
- Larry Antram 22 Oct 2002
C# will attract all comers, where VB is for IT Journalists and managers - Michael
P Butler 05-12-2002
It'd probably be fairly easy to make a bot that'd post random stupid VB questions, and nobody would probably ever notice - benjymous - 21-Jan-2003
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David Stone wrote:
Or just myObject.GetType();
Yeah, but don't you have to say
if (myobject.GEtType() == typeof(desiredtype)) ?
David Stone wrote:
BTW, how's that dynamic PDF solution look?
I just established that we have Acrobat 5.0, so I'm going to play with it tomorrow. I had to get something else together today for tomorrow's demo, and yesterday was a holiday here.
Christian
No offense, but I don't really want to encourage the creation of another VB developer.
- Larry Antram 22 Oct 2002
C# will attract all comers, where VB is for IT Journalists and managers - Michael
P Butler 05-12-2002
It'd probably be fairly easy to make a bot that'd post random stupid VB questions, and nobody would probably ever notice - benjymous - 21-Jan-2003
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Christian Graus wrote:
if (myobject.GEtType() == typeof(desiredtype))
typeof is just going to return the same thing as .GetType() will. They both have System.Type return values.
And, if you look at the remarks on the typeof page:
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/csref/html/vclrfTypeofPG.asp[^]...they say that in order to obtain the runtime type of the object, you should use GetType()
So the question is...what are you passing into typeof()?
[edit]Ah, I see now. The example makes it much clearer. You pass the name of a class into typeof(). GetType() returns the type of an object.[/edit]
[edit2]Besides, why wouldn't he just use the is keyword? if(myObject is Object)[/edit2]
Hey, what can I say? I'm a chick magnet...a babe conductor...a logarithm for the ladies.
-Strong Bad from HomeStarRunner.com
Essential Tips for Web Developers
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David Stone wrote:
typeof is just going to return the same thing as .GetType() will. They both have System.Type return values.
Ya. So if I want to know if an object is a string, I need typeof(string) to find that out, unless I arbitrarily create a string. No ?
David Stone wrote:
Besides, why wouldn't he just use the is keyword? if(myObject is Object
Dunno, I will check that out. I'm asking because I'm learning, too.  )
Christian
No offense, but I don't really want to encourage the creation of another VB developer.
- Larry Antram 22 Oct 2002
C# will attract all comers, where VB is for IT Journalists and managers - Michael
P Butler 05-12-2002
It'd probably be fairly easy to make a bot that'd post random stupid VB questions, and nobody would probably ever notice - benjymous - 21-Jan-2003
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Christian Graus wrote:
Ya. So if I want to know if an object is a string, I need typeof(string) to find that out, unless I arbitrarily create a string. No ?
Alrighty. After some looking around, I finally came to this conclusion:
typeof() takes in a class and spits out the System.Type information characterizing the class.
.GetType() returns the System.Type of the object you call it on.
Thus, remembering that an object is an instance of a class, you could techically do this:
MyObject myObject = new MyObject();
if(myObject.GetType() == typeof(MyObject))
However, using the is keyword is much faster because there isn't any extraction of the types by the CLR. It does some internal checking to see if they match...and then it'll return true if it works.
So that's what I've come to.
Hey, what can I say? I'm a chick magnet...a babe conductor...a logarithm for the ladies.
-Strong Bad from HomeStarRunner.com
Essential Tips for Web Developers
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This kind of comparison is defined with the IComparable interface. Anything that has an ordering should implememnt IComparable.
You should be able to cast the object you're storing to IComparable, and then call CompareTo(), passing in the other oject.
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This seems to be the most reasonable solution I will give it a try and let you know what happens.
Thanks for being helpful.
Michael
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Actually, the IComparable interface isn't going to help you. The CompareTo() method returns an int. It's for sorting lists.
You should however, use the "is" keyword in order to find out if it "is" an instance of that class. Don't use GetType() typeof() or even CompareTo(). Let's say you had a function that looked like this:
public void Cast(object obj)
{
if(obj is OneType)
{
OneType castedType = (OneType)obj;
{
else if(obj is AnotherType)
{
AnotherType castedType = (AnotherType)obj;
{
return;
}
If you really want dynamic casting, this is the way to do it. Using IComparable is not.
Hope that's clearer now.
Hey, what can I say? I'm a chick magnet...a babe conductor...a logarithm for the ladies.
-Strong Bad from HomeStarRunner.com
Essential Tips for Web Developers
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mgarwood wrote:
I would like to be able to do some sort of "dyanmic cast" on the data and call the appropriate CompareTo() method.
Something like this might help.
int Compare(object obj1, object obj2)
{
IComparable icom = obj1 as IComparable;
if (icom != null && obj2.GetType() == obj1.GetType())
return icom.CompareTo(obj2);
return int.MinValue;
}
MyDUMeter: a .NET DUMeter clone
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Will this work with primitive types as well (i.e. 'int', 'char', 'bool', 'short', long')?
If this will work this is the easiest and cleanest way. Before I got some suggestions I was leaning torwrds delegates but didn't really want to go there.
Thanks
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hello to list
any assistance much appreciated.
i apologise if this message loads slowly (received a warning when i sent). i live way out back, very slow connection, and i get email longer than this no problem)
why did the one project i did compile include syntax
different to the text book example? (staugaard, jr. structured and object oriented techniques, 2nd edition)
using borland 5.5.1 free command line tools with a command promt screen setup for me be a student list advisor so i type in 'complink <filename> to compile. i don't want to bother him further on this matter. couldn't figure out how to get a project to compile with borland 4.5, but have succedded in getting one to run with 5.5.1. i thought all i would have to do is use the same #include, #endif, etc, and all would be well. i think the enum is wrecking things in some small part, i can't find any information to show me rules for using enum's in structs. this code is probably a bit cut up by now.
you may have to fix the word wrap
you may assume i am rather green at this
/* *************************************** */
/* Yahtzee header file: */
#ifndef YATZ_H
#define YATZ_H
struct Play
{
private:
public:
int Score[ScoreMax+1];
int Dice[DiceMax+1];
void DisplayScoreCat(ScoreCat Cat);
void DisplayDice();
void Throw();
void Initialise();
};
#endif
/* *****************************************8 */
/* main file */
#include <iostream>
#include <iomanip>
#include <stdlib>
#include <time>
using namespace std;
#include "Yahzt.h"
const int ScoreMax=17;
const int DiceMax=5;
int main()
{
enum ScoreCat {Ones, Twos, Threes,
Fours, Fives, Sixes,
Three_of_a_Kind, Four_of_a_Kind, Full_House, Small_Straight,
Large_Straight, Yahtzee, Chance, Bonus, Upper_Total, Lower_Total,
Grand_Total};
ScoreCat Cat;
Play Game; // declare Game object
Game.Initialise();
time_t t;
srand((unsigned) time(&t));
cout<<"\n\n\t\tYatsee Game "
<<"\t\tScoring Catagories \n\n";
for(Cat = Ones; Cat <= Full_House; Cat =(ScoreCat) (Cat+1))
{
cout<<"\t\t"<<(Cat+1);
Game.DisplayScoreCat(Cat);
cout<<"-"<<Game.Score[Cat];
if(Cat<=3)
{
cout<<"\t"<<(Cat +10);
}
if(Cat<=7 )
{
Game.DisplayScoreCat(Cat+9);
cout<<"-"<<Game.Score[Cat+9];
}
cout<<endl;
}//end for
cout<<"\n\n";
Game.Throw();
Game.DisplayDice();
}
#include "Yahtz.cpp"
/* ***************************************** */
/* function file */
#include <iostream>
#include <iomanip>
#include <cstring>
using namespace std;
#include "Yahtz.h"
void Play::DisplayScoreCat(ScoreCat Cat)
{
switch(Cat)
{
case Ones: cout<<setw(18)<< "Ones"; break;
case Twos: cout<<setw(18)<< "Twos"; break;
case Threes: cout<< setw(18)<< "Thees"; break;
case Fours: cout<< setw(18)<< "Fours"; break;
case Fives: cout<< setw(18)<< "Fives"; break;
case Sixes: cout<< setw(18)<< "Sixes"; break;
case Three_of_a_Kind: cout<< setw(18)<< "3 of a Kind"; break;
case Four_of_a_Kind: cout<< setw(18)<< "4 of a Kind"; break;
case Full_House: cout<< setw(18)<< "Full House"; break;
case Small_Straight: cout<< setw(18)<< "Small Straight"; break;
case Large_Straight: cout<< setw(18)<< "Large straight"; break;
case Yahtzee: cout<< setw(18)<< "Yahtzee"; break;
case Chance: cout<< setw(18)<< "Chance"; break;
case Bonus: cout<< setw(23)<< "Bonus"; break;
case Upper_Total: cout<< setw(23)<< "Upper Total"; break;
case Lower_Total: cout<< setw(23)<< "Lower Total"; break;
case Grand_Total: cout<< setw(23)<< "Grand Total"; break;
cout<<"\t\tUnknown day"; break;
}
}
void Play::DisplayDice()
{
cout<<"\tThe 5 dice are :\n";
for(int i=0;i<5;i++)
{
cout<<Dice[i];
}
char console[4] [42]=
{
" 1 2 3 4 5 \n",
"----- ----- ----- ----- -----\n",
"| | | | | | | | | |\n",
"----- ----- ----- ----- -----\n"
};
for(int i=0; i<4; i++)
{
for(int j=0; j <42; j++)
{
if(j==0)
cout<<"\t\t";
if(j==2&&i==2)
{
console[i][j]=Dice[0];
}
if(j==11&&i==2)
{
console[i][j]=Dice[1];
}
if(j==20&&i==2)
{
console[i][j]=Dice[2];
}
if(j==29&&i==2)
{
console[i][j]=Dice[3];
}
if(j==38&&i==2)
{
console[i][j]=Dice[4];
}
cout<<console[i][j];
}
}
}
void Play::Throw()
{
for(int i=0; i<5; i++)
{
Dice[i]=(1+rand()%6);
}
}
void Play::Initialise()
{
for(int i=0; i<ScoreMax; i++)
{
Score[i]=0;
}
for(int i=0; i<DiceMax; i++)
{
Dice [i]=0;
}
}
/* **********************************************
error messages generated:
Borland C++ 5.5.1 for Win32 Copyright (c) 1993, 2000 Borland
Yahtzmain.cpp:
Error E2209 Yahtzmain.cpp 12: Unable to open include file 'Yahzt.h'
Error E2451 Yahtzmain.cpp 27: Undefined symbol 'Play' in function main()
Error E2379 Yahtzmain.cpp 27: Statement missing ; in function main()
Error E2451 Yahtzmain.cpp 29: Undefined symbol 'Game' in function main()
Error E2293 Yahtz.h 15: ) expected
Error E2147 Yahtz.cpp 12: 'ScoreCat' cannot start a parameter declaration
Error E2316 Yahtz.cpp 13: 'Play::DisplayScoreCat(int)' is not a member of 'Play'
Error E2206 Yahtz.cpp 35: Illegal character '\' (0x5c)
Error E2206 Yahtz.cpp 35: Illegal character '\' (0x5c)
*** 9 errors in Compile ***
*/
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You've posted this in the C# forum.
Christian
No offense, but I don't really want to encourage the creation of another VB developer.
- Larry Antram 22 Oct 2002
C# will attract all comers, where VB is for IT Journalists and managers - Michael
P Butler 05-12-2002
It'd probably be fairly easy to make a bot that'd post random stupid VB questions, and nobody would probably ever notice - benjymous - 21-Jan-2003
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please educate me.
i thought C# meant c, and some extention, like '++'
where should i have posted this query?
i thought i mentioned i am using borland 5.5.1,
i understood borland uses a much stricter form of c++ and vb is mainly for windows apps.
do you just hate c++, why? in my small understanding of the matter it seems to be the pick.
i still want to know what i'm doing wrong and c++ is all i know.
thank you for your response.
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You should go to the Visual C++ forum. They deal with all sorts of C++ problems in there...not just Microsoft related ones. C# is a new language by Microsoft made especially for the .NET platform and while it may look similar to C++, it isn't. Hope that clears things up.
Hey, what can I say? I'm a chick magnet...a babe conductor...a logarithm for the ladies.
-Strong Bad from HomeStarRunner.com
Essential Tips for Web Developers
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Funny joke. 
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