how to convert _variant_t to VARIANT*?

[BruceWho]

my application needs to use a COM component, one of the method uses a
VARIANT* data type like this:

void func(VARIANT* longVar);

and I handle VARIANT variables by _variant_t:

_variant_t var(100);

and now I need to pass var to func, and it doesnot work like this:

func(&var);

so could anybody figure me out how to convert this _variant_t to
VARIANT*?

[Egbert Nierop (MVP for IIS)]

Post by BruceWho
my application needs to use a COM component, one of the method uses a
void func(VARIANT* longVar);
_variant_t var(100);
func(&var);
so could anybody figure me out how to convert this _variant_t to
VARIANT*?

Hi Bruce,


This depends. In your case, I suspect that longVar is a *return* value?

If so

*longVar = var.Detach();
should be correct.

If *longVar is in/out you should attach first, and then detach.,

But if the variable is -really- a longVar, you don't need to worry about
memory leaks.

longVar->vt = VT_I4;
longVar->intVal = var.intVal;

should do the trick as well!

[Brian Muth]

Post by BruceWho
my application needs to use a COM component, one of the method uses a
void func(VARIANT* longVar);
_variant_t var(100);
func(&var);

But it does. The conversion is implied.

Brian

[BruceWho]

Yes, it indeed does. I made a mistake somewhere else.

thanks for your replies.

Post by Brian Muth

Post by BruceWho
my application needs to use a COM component, one of the method uses a
void func(VARIANT* longVar);
_variant_t var(100);
func(&var);

But it does. The conversion is implied.
Brian

[Alexander Nickolov]

Is this the exact method definition from the IDL file? This implies
a pure dispinterface, e.g. you need to call via IDispatch::Invoke.
--
=====================================
Alexander Nickolov
Microsoft MVP [VC], MCSD
email: ***@mvps.org
MVP VC FAQ: http://www.mvps.org/vcfaq
=====================================

Post by BruceWho
my application needs to use a COM component, one of the method uses a
void func(VARIANT* longVar);
_variant_t var(100);
func(&var);
so could anybody figure me out how to convert this _variant_t to
VARIANT*?