Re: what's the difference?

From:
"Thomas J. Gritzan" <phygon_antispam@gmx.de>
Newsgroups:
comp.lang.c++.moderated
Date:
Sun, 19 Apr 2009 02:57:22 CST
Message-ID:
<gsdk4a$ioq$1@newsreader2.netcologne.de>
Andrey Bulat wrote:

For instance for a function
void func(MyClass *pMyClass)
void func(MyClass& MyClass)
What's the difference of two? The first pass the address of the
MyClass,
how about the 2nd one?
usually which one is preferred?


Main difference is in early binding of reference type MyClass& and
possible late binding of pointer MyClass*
If you plan to use virtual functions you should use pointer:


If you read that in a book, throw it away.
Pointers and references are equal in respect to virtual functions and
early/late binding.

class MyClass{ virtual void f1(); }
class MyClass2: MyClass { virtual void f1(); }

void func(MyClass *pMyClass) { ... pMyClass->f1(); ....}

int main(){
MyClass* p = new MyClass2();
func(p);
}


This is functionally equivalent to:

void func2(MyClass& myClass) { ... myClass.f1(); ....}

int main() {
    MyClass* p = new MyClass2;
    func2(*p);
    // note: memory leak here
}

--
Thomas

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