how to get variable type

[Maxwell Chen]

Don't know... Regarding to typename CString specifically, it works well with my VC++.NET v7.0. I had tested the code snippet before I posted the previous post. And the code compiles well without any error / warning!

---

Maxwell Chen

[Maxwell Chen]

I used to zip my source code files (removed those .ncb, .opt, .plg, .\Debug, etc.) with separate file names (timestamp + hint) quite often to prevent such disasaters.

---

Maxwell Chen

[Curi0us_George]

Hmm. You're right. Your code's working on VS.NET2003 as well. Perhaps it's an incompatability between CString implementations? Or maybe he's using VC6, and it's failing to match the standards in this area.

[Andrew Walker]

When you get going again, maybe you could try a template specialisation, which avoids the need for typeid or dynamic_cast's by making the compiler do the work for you. This specialisation is so simple that it should :) work even under VC6

template<class T>
void f(T t)
{
    // do nothing
}

template<>
void f<CString>(CString t)
{
    OutputDebugString(t);
}

// ... snip
    int i = 0;
    f(i);
    CString str = "hello world";
    f(str);
// ... snip

---

If you can keep you head when all about you Are losing theirs and blaming it on you; If you can dream - and not make dreams your master; If you can think - and not make thoughts you aim; Yours is the Earth and everything that's in it. Rudyard Kipling

[Maxwell Chen]

In VC++6, it's an ordinal class CString. In VC++7.x, it's a class template CStringT<typename N>. And typedefed CStringT<char> as CString. Maybe that's the cause... :~

---

Maxwell Chen

[Curi0us_George]

Apparently so. I guess I'm not quite clear on what counts as a polymorphic type, though. Maybe templates are special or something, but I couldn't find any virtual functions in CString or its superclass. It seems to me that it still shouldn't qualify as a polymorphic type, and therefore dynamic_cast shouldn't work.

[closecall]

yes i am using vc++6.0 i will try the typeid method once i re-write all my lost codes :| My initial intention was to come up with a global class that can convert a variable of type A to type B at run-time.

[Maxwell Chen]

Remember to turn on the RTTI (run-time type information) option in VC++ project setting.

---

Maxwell Chen

[closecall]

aaaaahh... thats what they mean by run time type information !!! haha.

[Mahendra_786]

What vc 7.x is doing seems more logical than vc 6.0 ... it seems to be checking the "from" and "to" types! class A { int a; }; class B: public A { int b; }; /***** break ****/ B b; if (dynamic_cast**(&b)) { printf("OK"); } /***** above will work in vc 7.x but not vc 6.0 */ /***** below will NOT work in both vc 7.x & vc 6.0 */ B b; A *p_a = &b; if (dynamic_cast**(p_a)) { printf("OK"); }****

[toxcct]

did you try **typeid**() ??:-D

---

TOXCCT >>> GEII power

[Anthony_Yio]

For non RTTI way You could try IsKindOf (Of course, this is not as good as RTTI. As this was invented by Microsoft before the time where RTTI was approved by ANSI.) For RTTI you could try type_info or the one they mentiond dynamic_cast.. Sonork 100.41263:Anthony_Yio Life is about experiencing ...

[David Crow]

For MFC objects, have you looks at IsKindOf()?

---

"The pointy end goes in the other man." - Antonio Banderas (Zorro, 1998)