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Most likely the first column of the first row in result is not an int (but for example DbType.Decimal etc).
If you get InvalidCastException, the exception along with the stack should show you what you are actually trying to cast to int.
The need to optimize rises from a bad design
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Yes, DaveyM69's right, it's possible that your cmd.ExecuteScalar() returns null so you can't convert it like this,
ctknox wrote: int id = (int)cmd.ExecuteScalar();
try following to understand:
string str = null;
int i = (int)str;
int j = Convert.ToInt32(str);
While (true) { Human.isLearnable = true; }
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This is a tricky one. ExecuteScalar returns an object. This means that if it returns an int, it will be wrapped as a "boxed" int, similarily if its actually returning something like an unsigned int, you'll get a boxed unsigned int.
Boxed ints can be cast to an int. Unsigned ints can be cast to an int.
Boxed unsigned ints cannot be cast to an int.
int x = (int)5L;
int y = (int)(object)5;
int z = (int)(object)5L;
Convert.ToInt32 works (and I had to look into this before so I'm only going on memory) because it uses the IConvertible interface. (It also does a null-check as well, and returns zero - which might be another reason your casting code could fail).
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Hi all,
This is simple thinking concept query is that-I've an one abstract class that contain some method test() and i've one interface in that with same signature of abstract class method test() name ok fine.(they are just declared)
now i want to implement in one class. And i called and provided some functionalities to the 2 methods, 1 is from abstract class and 1 is from interface .
so how to call particular interface method with the class object that we are implemented in the class and how to call abstract class method with the class object.-
bcoz are 2 same named methods and with the signature also same..........so how would know when we are declared object for class and calling some obj.test()-which method will displayed-is it from abstract or interface belonged method. can u plz give me reply very soon............
modified on Thursday, October 9, 2008 2:50 AM
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Quick answer: Interfaces do not have implementations, classes do. So you don't have two different methods.
The need to optimize rises from a bad design
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I mean that interface has only signature method that method name test(),similarly abstract class has same method test() with same signature of interface.That 2 methods are just declared.
Now in my class i provided functionalities for those methods by inheriting both abstract and interface.
Up to this okey ,now i declared one object for class calling method test() with that object.........so which method will be called ........either abstract class method or interface method.
and why do u get that
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Okay,
Few things: You inherit from abstract class, meaning you get some functionality. You don't inherit from interface, you implement it. This means, that when you implement an interface, you must write the implementation logic for the method defined in an interface.
In your situation, the abstract class may create the implementation for the interface or if the abstract class doesn't do that, you must do it in inherited class
Mika
The need to optimize rises from a bad design
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Sorry u could n't get my question.
First i want to inheritance and implements methods of abstract class and interface(But here the 2 one is abstract class contain test() method,other one interface contain test() method. both are same in signature.)
so I did inheritance and implementation for abstract class and interface in the class.Up to here fine...when declare a object for class and calling test() method with the class object so which of method will be called in the class ,either from implemented interface method or abstract class method.Bcoz they have same signature of two methods that is why am asking.
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Could you post the code or simplified sample. This would greatly help me to see the issue.
The need to optimize rises from a bad design
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Hi,
I have to wirte a Parser, and therfore I would need all the variables and functions definded in a C file. I realiced there is a class called Codedom, but don't know if it is what I search for. If not do you know any other ways to get variables and functions from a C-file?
Thanks for your help.
Dromar
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If you can read the code (for example from a file), compile it and investigate fields, functions etc without actually parsing it yourself, CodeDOM should be useful.
If you really want to parse the original yourself, have a look at for example Yacc[^] which can also be found for Windows.
The need to optimize rises from a bad design
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Just to make clear what I want.
I have a Sourcefile (c, cpp, h...) and want to check if the pass certian programming rules (in my case the MISRA-C 2004 rules). Therefore I need all the Variables and Functions. Can I do that with the Codedom? And if yes can you please post me an example?
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Hi, take a look at Irony .NET. you can find references here in CP. It's well worth to take a look, I think it does what you want.
Intelligence is almost useless for those who have nothing else!
Email: caiokf@gmail.com
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Irony is quite good.
As is PerCendburg(?) Grammatica. Used that for quite a few projects where I've had a configuration DSL.
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Hi any one.
i want to create some class library and allow user to add it some data in a Collection.(example of it is Items property in Combobox or listbox).
i define a Dictionary collection and when using , it appear in control library but when i click it to add some data it show a disabled window.
its my public property:
public Dictionary<int32,> States
{
get
{
return MySexCell.States;
}
set
{
MySexCell.States = value;
}
}
sepel
modified on Tuesday, October 7, 2008 2:01 PM
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sepel wrote: public Dictionary<int32,> States
Does that even compile? You need two datatypes in a Dictionary definition, one type for the key and one for the value.
Perhaps you should use a List instead of a Dictionary?
Despite everything, the person most likely to be fooling you next is yourself.
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I'm to being DIZZY .
i write dictionary (int32,string)but it dosen't appear.(using "(" instade of "<")
take it easy . i try to use List.
But think about this forum syntax way does not appear my code.
I test another type for my second Dictionary parameter but after post it no one appear.
sepel
modified on Tuesday, October 7, 2008 1:52 PM
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MySexCell? *sniggers* Just what kind of application is this?
You probably don't want to expose a "set" accessor. That is if you want people to change the entire dictionary. People can "get" the dictionary and then call .Add on it.
You need to google the correct attributes to put on your property to enable designer support.
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Hahahah.(MySexCell)
it is a cell that for male or female that saved in bit format in db, show corespond string such as "man or woman or Mr or
Mrs,...".
i think i should use Attribute . tnx
sepel
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Suppose I have this class:
public abstract class EmployeeBase
{
public string _sEmpName = "Some One";
public int _iPayRate = 0;
public abstract string sEmpName
{
get;set;
}
public abstract int iPayRate
{
get;set;
}
public abstract void CalcPay();
}
I then subclass it as:
public class FTEmployee : EmployeeBase
{
private new string _sEmpName;
private new int _iPayRate = 0;
public override string sEmpName
{
get {return _sEmpName;}
set {_sEmpName = value;}
}
public override int iPayRate
{
get {return _iPayRate;}
set {_iPayRate = value;}
}
public override void CalcPay()
{
}
}
I'm trying to define the _sEmpName member in the base class and make it private in the subclass, but when I test it, the _sEmpName member contains Null.
Can someone help a newbie?
Everything makes sense in someone's mind
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KMAROIS wrote: when I test it, the _sEmpName member contains Null.
Not in the base class it isn't.
You have two _sEmpName members - one in the base class and one
in the derived class.
Sounds like you just need the one in the base class.
Only methods/accessors can be abstract.
Mark
Mark Salsbery
Microsoft MVP - Visual C++
![Java | [Coffee]](https://www.codeproject.com/script/Forums/Images/coffee.gif)
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What I'm trying to do is define the member in the base, then make it private in the subclass so that the property implementations can access it.
When I made the members private in the base I get the error
"Abstract.EmployeeBase._sEmpName' is inaccessible due to its protection level"
Everything makes sense in someone's mind
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KMAROIS wrote: When I made the members private in the base I get the error
"Abstract.EmployeeBase._sEmpName' is inaccessible due to its protection level"
Correct. As John mentions below, you can't access a private member
outside the class, including derived classes.
Try protected instead.
Mark
Mark Salsbery
Microsoft MVP - Visual C++
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Make the variables private in the base class and don't define them in the derived class since you inherit them
KMAROIS wrote: public abstract class EmployeeBase
{
private string _sEmpName = "Some One";
private int _iPayRate = 0;
KMAROIS wrote: public class FTEmployee : EmployeeBase
{
private new string _sEmpName;
private new int _iPayRate = 0;
led mike
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