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Divyang Mithaiwala wrote: Because if you have taken temp as array (char temp[XX]) then you might get error
 Why so?
Divyang Mithaiwala wrote: But a code that we are sawing has no that kind of error.
Did you trust your computer to check if there was a runtime error? 
You need to google first, if you have "It's urgent please" mentioned in your question.
 _AnShUmAn_
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sorry, But I really didnot get that
-----------------------------
I am a beginner
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When I was posted I haven't seen your clarification that you are facing run time error (due to no refresh page).
So, If you have taken variable as char temp[10]; and try to execute
*temp++ = *a++;
it will give you compile time error.
Do not trust a computer...
Always check what computer is doing
regards,
Divyang Mithaiwala
Software Engineer
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I haven't tested that nor tried something similar, but I think that the hole think wont give you the right result anyway.
By incrementing the char * temp it jumps to the next position and you will lose the previous position, don't you?
So if you really want to do something like that you should have a pointer to the first position of temp (I guess).
So why not simply allocate mem for temp and then do a memcpy with a and b? Given memcpy temp and for b &temp[2] for example.
I hope this will do the trick, but I am just guessing.
Cheers
You have the thought that modern physics just relay on assumptions, that somehow depends on a smile of a cat, which isn’t there.( Albert Einstein)
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I have delphi application .I am trying to convert it into c++ builder
this is my delphi function
function TClipCollection.GetItem(Index: Integer): TClipItem;
begin
Result := inherited Items[Index] as TClipItem;
end;
and this is my builder function
TClipItem TClipCollection::*GetItem(int Index)
{
// Result := inherited Items[Index] as TClipItem;
how i convert this line
}
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Probably something like
TClipItem* TClipCollection::GetItem(int Index)
{
return (TClipItem*)Items[Index];
}
You need to be sure that the array indices are consistent between Delphi and C++ (C++ array indices start at zero - do Delphi array indices do the same?).
Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p
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thanks Stuart Dootson
but i am now getting error
E2451 Undefined symbol 'Items'
where as i defined the property in the TClipCollection class
__property TClipItem *Items[int Index] = { read=GetItem, write=SetItem};
for more details my class like this
class TClipCollection : public TCollection
{
private:
TClipItem *GetItem(int Index);
void SetItem(int Index,TClipItem *Value);
public:
TClipCollection();
__property TClipItem *Items[int Index] = { read=GetItem, write=SetItem};
TClipItem Add();
TClipCollectionEnumerator GetEnumerator();
};
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How are you using Items? It looks to me like the compiler and linker are seeing Items as a global symbol (i.e. not a class member).
Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p
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but in delphi it is used
delphi code is this
TClipCollection = class(TCollection)
private
function GetItem(Index: Integer): TClipItem;
procedure SetItem(Index: Integer; const Value: TClipItem);
public
constructor Create;
property Items[Index: Integer]: TClipItem read GetItem write SetItem; default;
function Add: TClipItem;
function GetEnumerator: TClipCollectionEnumerator;
end;
you r right and when i mke the constructor of this class then i got also error
E2251 Cannot find default constructor to initialize base class 'TCollection'
then what i do for this
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rajeshkumarrajput wrote: but in delphi it is used
Delphi is a different language than C++ - it has different rules - and anyway, I asked you how Items was used in your code - it's the use of something called Items, not the definition that's causing that error.
I suspect your GetItem/SetItem code is overriding the relevant property accessors from TCollection, so you probably need something like:
TClipItem* TClipCollection::GetItem(int index)
{
return (TClipItem*)(((TCollection*)this)->Items[index]);
}?
rajeshkumarrajput wrote: E2251 Cannot find default constructor to initialize base class 'TCollection'
That'll be because TCollection has no default constructors - look at the documentation (C++ Builder has documentation, I presume?) and work out which constructor you should be using.
Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p
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now i am getting the error
E2297 'this' can only be used within a member function
can i send my code to solve the problem ?
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I'd suggest you might want to learn C++ instead - that'll be more use in the long run.
Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p
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thanks Stuart Dootson
for help
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I need to crate template class which will be generic parent of more classes containing data. Each child class defines something like item ID (different name in each class, but always int) and I need to let parent class know it's name to be able to make some operations on that.
This is pseudocode:
template <class T, ???XXX > class DRecord
{
void DoReset() { ((T*)this) -> XXX = 0; }
}
class A : public DRecord<A, ???A_XXX >
{
int A_XXX;
}
XXX is template param I need to define and use some way. I've tried to use member pointers but it didn't compile. Is it possible to define member of child class as parameter into parent class? In moment of parsing the template the member variable is not declared yet, so I'm not sure whether is it possible.
Thank you.
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Why do you want to do that?
Could just use polimorphism, couldn't you?
If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.
This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong.
-- Iain Clarke
[My articles]
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I'm creating some database wrapper, it maps tables to classes (or structures). There are some common operations I need to do on primary keys, but each table is using different PK names. I want to code common operations only once (using templates, not preprocessor macros unless necessary) and don't want to use virtual functions (it should be theoretically possible, but I don't know whether C++ templates are powerful enough for this).
It is also interesting problem for me since I'm not template expert and I'd like to learn
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rrrado wrote: and don't want to use virtual functions
Why don't you (you know base classes practically imply this...  )?
If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.
This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong.
-- Iain Clarke
[My articles]
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Because it is not necessary to use virtual tables just to make simple job Just for one function <pre>virtual int& GetID();</pre> There are more ways how to do this but I'd like to use clean solution.
I have solution with templates for this but it is using extra class and multiple inheritance so I don't like it.
This could be useful for me also in future for different purposes so I'd like to know
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rrrado wrote: Because it is not necessary to use virtual tables just to make simple job Smile Just for one function
virtual int& GetID();
Since this is your point of view, why do you ask for a 'clean solution'?
If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.
This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong.
-- Iain Clarke
[My articles]
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How about just presuming the existence of accessor functions in the parent - I've defined a macro to help reduce the amount of typing:
template <class T> class DRecord
{
void DoReset() { static_cast<T*>(this)->SetID(0); }
};
#define DEFINE_ID_FIELD(ID_NAME) \
int NAME;
void SetID(int value) { NAME = value; }
int GetID(int value) const { return NAME; }
class A : public DRecord<A>
{
DEFINE_ID_FIELD(A_XXX)
};
As an aside - are you aware of the OLE DB consumer templates[^] - they're templated database wrappers...
Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p
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Thank you for idea, I was thinking about it and haven't realized that I don't need virtual accessors for this unless I saw your code.
I don't know OLE DB templates, thank you for tip. I'm using sqlite so I guess I cannot use them but maybe there will be some good point in their architecture.
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rrrado wrote: I don't know OLE DB templates, thank you for tip. I'm using sqlite so I guess I cannot use them...
I wouldn't bet on it - OLE DB Provider for SQLite[^]
Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p
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i'm in an exam. and that's the question. i'vw 2 hours to answer it. thank you.
1. Write a class shape with a constructor that takes no parameters and outputs the message created a shape. The class should have two data members, area and perimeter. Write a main function to test the class by creating an object of the class shape.
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Please tell us where you are stuck. We can help you out.
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Try to code it instead of wasting time on forums.
BTW it should take, at least 10 minutes.
If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.
This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong.
-- Iain Clarke
[My articles]
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