typecasting ???

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cmrchs@yahoo.com - 05 Jul 2005 17:38 GMT

Hi,

what is the way to check whether a value is truly a boolean :

I try the following:

Object ^obj = m_XPathNav->Evaluate(<some xpath expression>);

if (nullptr != static_cast<double^>(obj) )
sMessage = "double";
else if (nullptr != static_cast<bool^>(obj) )
sMessage = "boolean";

Even with boolean values does the first typecast always return true so I always get "double"

In C# there exist the is-operator that clearly makes a distinction.
Is there a C++ - version of the is-operator ?

thanks
Chris

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Carl Daniel [VC++ MVP] - 05 Jul 2005 17:57 GMT

Chris C wrote:

> Hi,
>
[quoted text clipped - 14 lines]
> In C# there exist the is-operator that clearly makes a distinction.
> Is there a C++ - version of the is-operator ?

Here's a small sample:

#using <mscorlib.dll>

using namespace System;

void test(String^ name, Object^ obj)
{
Console::Write("{0}: ",name);
if (obj->GetType() == Boolean::typeid)
Console::WriteLine("Yes");
else
Console::WriteLine("No");
}

int main()
{
test("double",1.0);
test("bool",true);
test("int",5);
}

-cd

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cmrchs@yahoo.com - 05 Jul 2005 18:01 GMT

thanks, I'll try that !

using dynamic_cast<> works as well of course (= standard C++)

greetz
Chris

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typecasting ???

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