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GeneralRe: Open image file with file dialog and use it in the same program run Pin
raouaa29-May-09 2:43
raouaa29-May-09 2:43 
QuestionPeopleSoft_PeopleSoft.tlb Pin
BabuRao.k28-May-09 2:15
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AnswerRe: PeopleSoft_PeopleSoft.tlb Pin
Mike Marynowski28-May-09 2:21
professionalMike Marynowski28-May-09 2:21 
AnswerRe: PeopleSoft_PeopleSoft.tlb Pin
Mike Marynowski28-May-09 2:27
professionalMike Marynowski28-May-09 2:27 
QuestionConversion --- need explanation Pin
u060509428-May-09 1:51
u060509428-May-09 1:51 
AnswerRe: Conversion --- need explanation Pin
Rob Philpott28-May-09 2:16
Rob Philpott28-May-09 2:16 
GeneralRe: Conversion --- need explanation Pin
u060509428-May-09 5:54
u060509428-May-09 5:54 
GeneralRe: Conversion --- need explanation Pin
Rob Philpott28-May-09 6:10
Rob Philpott28-May-09 6:10 
Ok, this is all known as polymorphism and is the backbone of object oriented programming.

Firstly, the purpose of a reference type. They didn't exist in languages such as C++, you could create anything either on the heap or the stack, it was your choice. The rules in .NET are a bit more restrictive in that all reference types end up on the heap. It's the concept of maintaining a reference to a thing rather than the thing itself (which absolutely speaking isn't really correct). You can for example have two references to the same object instance. Try that with a value type and you could easily run into problems.

Animal z = new Cat();

Here you have an animal reference to a cat instance. When you call Talk(), whether Animal.Talk() gets called or Cat.Talk() gets called depends on whether that method has been marked as virtual.

If not virtual Animal.Talk() gets called, hopefully for obvious reasons. If the method is virtual however, the runtime will start working through something that used to be called a v-table (don't know what it is in .net) based on the type of the instance not the type of the reference. Cat.Talk() gets called.

This way you can implement Cat.Talk, Dog.Talk, Chicken.Talk, treat any of them as an animal, and call Talk() and it will get resolved to the correct method.

Regards,
Rob Philpott.

GeneralRe: Conversion --- need explanation Pin
OriginalGriff28-May-09 6:19
mveOriginalGriff28-May-09 6:19 
GeneralRe: Conversion --- need explanation Pin
Rob Philpott28-May-09 6:22
Rob Philpott28-May-09 6:22 
GeneralRe: Conversion --- need explanation Pin
u060509430-May-09 2:51
u060509430-May-09 2:51 
GeneralRe: Conversion --- need explanation Pin
OriginalGriff28-May-09 6:14
mveOriginalGriff28-May-09 6:14 
AnswerRe: Conversion --- need explanation Pin
PIEBALDconsult28-May-09 3:26
mvePIEBALDconsult28-May-09 3:26 
Questionexecuting code in a textbox on runtime Pin
WinSolution28-May-09 1:35
WinSolution28-May-09 1:35 
QuestionRe: executing code in a textbox on runtime Pin
Rajesh R Subramanian28-May-09 1:50
professionalRajesh R Subramanian28-May-09 1:50 
AnswerRe: executing code in a textbox on runtime Pin
WinSolution28-May-09 2:12
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GeneralRe: executing code in a textbox on runtime Pin
molesworth28-May-09 2:39
molesworth28-May-09 2:39 
GeneralRe: executing code in a textbox on runtime Pin
WinSolution28-May-09 3:39
WinSolution28-May-09 3:39 
GeneralRe: executing code in a textbox on runtime Pin
Searril28-May-09 5:21
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AnswerRe: executing code in a textbox on runtime Pin
Giorgi Dalakishvili28-May-09 2:41
mentorGiorgi Dalakishvili28-May-09 2:41 
QuestionRe: executing code in a textbox on runtime Pin
harold aptroot28-May-09 3:26
harold aptroot28-May-09 3:26 
AnswerRe: executing code in a textbox on runtime Pin
WinSolution28-May-09 3:46
WinSolution28-May-09 3:46 
GeneralRe: executing code in a textbox on runtime Pin
harold aptroot28-May-09 3:54
harold aptroot28-May-09 3:54 
GeneralRe: executing code in a textbox on runtime Pin
molesworth28-May-09 4:49
molesworth28-May-09 4:49 
GeneralRe: executing code in a textbox on runtime Pin
WinSolution29-May-09 3:48
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