Re: checking for instance validity - C / C++ / MFC Discussion Boards

Re: checking for instance validity

rp_suman15-Feb-08 0:53

rp_suman

15-Feb-08 0:53

He might have meant different person,

Best Regards,
Suman Smile | :)

Re: checking for instance validity

Rajesh R Subramanian15-Feb-08 1:21

Rajesh R Subramanian

15-Feb-08 1:21

There's a thing called pun. And one more thing called "the joke icon". Hmmm | :|

Nobody can give you wiser advice than yourself. - Cicero
.·´¯`·->Rajesh<-·´¯`·.
Codeproject.com: Visual C++ MVP

Re: checking for instance validity

rp_suman15-Feb-08 0:35

rp_suman

15-Feb-08 0:35

For example, if we create some object using new() and call delete(), the object will be deleted.
I want to avoid the use of the object before new() and after delete().
Can we check like if(object != NULL) or else?

BTW:
Sorry for delay I posted just before leaving office, now seeing from my room.
Best Regards,
Suman

Re: checking for instance validity

Cedric Moonen15-Feb-08 0:52

Cedric Moonen

15-Feb-08 0:52

Yes, just set the pointer to NULL in your constructor and once you delete the object, just set it to NULL again.

Cédric Moonen
Software developer

Charting control [v1.2]

Re: checking for instance validity

rp_suman15-Feb-08 0:56

rp_suman

15-Feb-08 0:56

So, I can check the object is not NULL before accessing it.

Thanks & Regards,
Suman

Re: checking for instance validity

Cedric Moonen15-Feb-08 1:01

Cedric Moonen

15-Feb-08 1:01

Onlyl if you are working with pointers because if you are working with objects directly, they are always "valid" (except if you did something really wrong, but anyway, there's no way to test it).

Cédric Moonen
Software developer

Charting control [v1.2]

Re: checking for instance validity

rp_suman15-Feb-08 1:08

rp_suman

15-Feb-08 1:08

Hi Cedric, you are right..
Thanks for the great help!!

Best Regards,
Suman

Re: checking for instance validity

ThatsAlok14-Feb-08 22:06

ThatsAlok

14-Feb-08 22:06

rp_suman wrote:
How to check the instance of the class is valid or it is not especially in multi threaded program?

is that pointer to class or simple object!

"Opinions are neither right nor wrong. I cannot change your opinion. I can, however, change what influences your opinion." - David Crow
Never mind - my own stupidity is the source of every "problem" - Mixture

cheers,
Alok Gupta
VC Forum Q&A :- I/IV
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Re: checking for instance validity

rp_suman15-Feb-08 0:36

rp_suman

15-Feb-08 0:36

Simple object and also pointer.

Thanks & Regards,
Suman

Re: checking for instance validity

Rajesh R Subramanian15-Feb-08 1:24

Rajesh R Subramanian

15-Feb-08 1:24

How's life, Alok? Smile | :)

(Brahmma here... Changed the CP display name to my real name)

Nobody can give you wiser advice than yourself. - Cicero
.·´¯`·->Rajesh<-·´¯`·.
Codeproject.com: Visual C++ MVP

Re: checking for instance validity

ThatsAlok15-Feb-08 7:15

ThatsAlok

15-Feb-08 7:15

ffine buddy.. what abt you

cheers,
Alok Gupta
VC Forum Q&A :- I/IV
Support CRY- Child Relief and You/codeProject$$>

Re: checking for instance validity

Rajesh R Subramanian15-Feb-08 20:06

Rajesh R Subramanian

15-Feb-08 20:06

Me doing good, Alok. Thanks. Smile | :)

Nobody can give you wiser advice than yourself. - Cicero
.·´¯`·->Rajesh<-·´¯`·.
Codeproject.com: Visual C++ MVP

Re: checking for instance validity

David Crow15-Feb-08 3:42

David Crow

15-Feb-08 3:42

The whole essence of an object is that it knows about itself. Add an IsValid() method to the class. When that method is invoked, the object can check the validity of each of its members.

"Normal is getting dressed in clothes that you buy for work and driving through traffic in a car that you are still paying for, in order to get to the job you need to pay for the clothes and the car and the house you leave vacant all day so you can afford to live in it." - Ellen Goodman

"To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne

Re: checking for instance validity

rp_suman15-Feb-08 4:41

rp_suman

15-Feb-08 4:41

IsValid () is defined in which class of C++?

Thanks & Regards,
Suman

Re: checking for instance validity

David Crow15-Feb-08 4:49

David Crow

15-Feb-08 4:49

Did you miss the "Add an IsValid() method to the class" part?

Re: checking for instance validity [modified]

rp_suman15-Feb-08 5:41

rp_suman

15-Feb-08 5:41

Hi, so you mean IsValid() is the user defined method?
I have doubt, can we check the object of CStringList is valid like if(object != NULL)?

Thanks & Regards,
Suman

modified on Friday, February 15, 2008 11:51 AM

definition of ITypeInfo

George_George14-Feb-08 21:17

George_George

14-Feb-08 21:17

Hello everyone,

Could anyone post or let me know where is the definition of ITypeInfo please?

(my purpose is to find its inheritance relationship, i.e. whether inherits from IUnknown or something)

I searched all VC sub-directory and only get (in afxstat_.h),

struct ITypeInfo;
typedef ITypeInfo* LPTYPEINFO;

thanks in advance,
George

Re: definition of ITypeInfo

Rajkumar R14-Feb-08 22:00

Rajkumar R

14-Feb-08 22:00

Oaidl.h ?

George_George wrote:
where is the definition of ITypeInfo please

u mean declaration

George_George wrote:
my purpose is to find its inheritance relationship, i.e. whether inherits from IUnknown or something)

yes it inherits from IUnknown

Re: definition of ITypeInfo

George_George14-Feb-08 22:14

George_George

14-Feb-08 22:14

Thanks Rajkumar,

Cool, I have found it from Oaidl.h. I am interested that Oa is short for?

MIDL_INTERFACE("00020401-0000-0000-C000-000000000046")
ITypeInfo : public IUnknown
{
public:
    virtual /* [local] */ HRESULT STDMETHODCALLTYPE GetTypeAttr(
        /* [out] */ TYPEATTR **ppTypeAttr) = 0;

    virtual HRESULT STDMETHODCALLTYPE GetTypeComp(
        /* [out] */ ITypeComp **ppTComp) = 0;

    virtual /* [local] */ HRESULT STDMETHODCALLTYPE GetFuncDesc(
        /* [in] */ UINT index,
        /* [out] */ FUNCDESC **ppFuncDesc) = 0;

    virtual /* [local] */ HRESULT STDMETHODCALLTYPE GetVarDesc(
        /* [in] */ UINT index,
        /* [out] */ VARDESC **ppVarDesc) = 0;

    virtual /* [local] */ HRESULT STDMETHODCALLTYPE GetNames(
        /* [in] */ MEMBERID memid,
        /* [length_is][size_is][out] */ BSTR *rgBstrNames,
        /* [in] */ UINT cMaxNames,
        /* [out] */ UINT *pcNames) = 0;

    virtual HRESULT STDMETHODCALLTYPE GetRefTypeOfImplType(
        /* [in] */ UINT index,
        /* [out] */ HREFTYPE *pRefType) = 0;

    virtual HRESULT STDMETHODCALLTYPE GetImplTypeFlags(
        /* [in] */ UINT index,
        /* [out] */ INT *pImplTypeFlags) = 0;

    virtual /* [local] */ HRESULT STDMETHODCALLTYPE GetIDsOfNames(
        /* [size_is][in] */ LPOLESTR *rgszNames,
        /* [in] */ UINT cNames,
        /* [size_is][out] */ MEMBERID *pMemId) = 0;

    virtual /* [local] */ HRESULT STDMETHODCALLTYPE Invoke(
        /* [in] */ PVOID pvInstance,
        /* [in] */ MEMBERID memid,
        /* [in] */ WORD wFlags,
        /* [out][in] */ DISPPARAMS *pDispParams,
        /* [out] */ VARIANT *pVarResult,
        /* [out] */ EXCEPINFO *pExcepInfo,
        /* [out] */ UINT *puArgErr) = 0;

    virtual /* [local] */ HRESULT STDMETHODCALLTYPE GetDocumentation(
        /* [in] */ MEMBERID memid,
        /* [out] */ BSTR *pBstrName,
        /* [out] */ BSTR *pBstrDocString,
        /* [out] */ DWORD *pdwHelpContext,
        /* [out] */ BSTR *pBstrHelpFile) = 0;

    virtual /* [local] */ HRESULT STDMETHODCALLTYPE GetDllEntry(
        /* [in] */ MEMBERID memid,
        /* [in] */ INVOKEKIND invKind,
        /* [out] */ BSTR *pBstrDllName,
        /* [out] */ BSTR *pBstrName,
        /* [out] */ WORD *pwOrdinal) = 0;

    virtual HRESULT STDMETHODCALLTYPE GetRefTypeInfo(
        /* [in] */ HREFTYPE hRefType,
        /* [out] */ ITypeInfo **ppTInfo) = 0;

    virtual /* [local] */ HRESULT STDMETHODCALLTYPE AddressOfMember(
        /* [in] */ MEMBERID memid,
        /* [in] */ INVOKEKIND invKind,
        /* [out] */ PVOID *ppv) = 0;

    virtual /* [local] */ HRESULT STDMETHODCALLTYPE CreateInstance(
        /* [in] */ IUnknown *pUnkOuter,
        /* [in] */ REFIID riid,
        /* [iid_is][out] */ PVOID *ppvObj) = 0;

    virtual HRESULT STDMETHODCALLTYPE GetMops(
        /* [in] */ MEMBERID memid,
        /* [out] */ BSTR *pBstrMops) = 0;

    virtual /* [local] */ HRESULT STDMETHODCALLTYPE GetContainingTypeLib(
        /* [out] */ ITypeLib **ppTLib,
        /* [out] */ UINT *pIndex) = 0;

    virtual /* [local] */ void STDMETHODCALLTYPE ReleaseTypeAttr(
        /* [in] */ TYPEATTR *pTypeAttr) = 0;

    virtual /* [local] */ void STDMETHODCALLTYPE ReleaseFuncDesc(
        /* [in] */ FUNCDESC *pFuncDesc) = 0;

    virtual /* [local] */ void STDMETHODCALLTYPE ReleaseVarDesc(
        /* [in] */ VARDESC *pVarDesc) = 0;

};

regards,
George

Re: definition of ITypeInfo

Rajkumar R14-Feb-08 22:22

Rajkumar R

14-Feb-08 22:22

OA - OLE Automation, not sure Smile | :)

BTW, use bandwidth wisely. I don't think in this context posting code is necessary.

Re: definition of ITypeInfo

George_George14-Feb-08 22:42

George_George

14-Feb-08 22:42

Thanks for your advice, Rajkumar!

Seems you have a lot of experience of COM, how about my another question about IDispatch? Smile | :)

http://www.codeproject.com/script/Forums/View.aspx?fid=1647&msg=2428711[^]

regards,
George

How to Display HTML strings in MFC ?

Sharath Jagannath14-Feb-08 20:37

Sharath Jagannath

14-Feb-08 20:37

How to Display HTML strings in MFC ? Tried it with DHtmlEdit but is it possible to make it read only Smile | :)

. My requirement is display a HTML string but they are not to be edited and i don't want to create a HTML file to use navigate () function of CWebBrowser. Did bit of R&D Smile | :)

but with no result though.

Re: How to Display HTML strings in MFC ?

Rajesh R Subramanian14-Feb-08 20:41

Rajesh R Subramanian

14-Feb-08 20:41

So, what is HTML strings? Do you mean you'd like to display some HTML content?

Re: How to Display HTML strings in MFC ?

Sharath Jagannath14-Feb-08 20:47

Sharath Jagannath

14-Feb-08 20:47

HTML Strings mean, I create HTML Tags in the memory and doesn't want to create an HTML file to display them, I need to display them directly onto a browser and i failed to find out a way. Tried doing the same using WebBrowser2 ActiveX control but it required only Html File path as it's input in Navigate and also tried DHtmlEdit but i was able to edit the contents using it, which is not required

Re: How to Display HTML strings in MFC ?

Sharath Jagannath14-Feb-08 20:48

Sharath Jagannath

14-Feb-08 20:48

and thx for the help Wink | ;)

in advance

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