前项引用声明 - 编程论坛

#2

cclearner2007-07-05 23:50

没人能指点一下迷津么？
我的前项引用声明。。。。。。

#3

野比2007-07-05 23:58

没时间了... 明晚来看看... 估计HJin, aipb等很快能给你回答...
祝顺利解决...

#4

HJin2007-07-06 06:20

回复：（cclearner）前项引用声明

/*---------------------------------------------------------------------------
File name: declVSdefn.cpp
Author: HJin (email: fish_sea_bird [at] yahoo [dot] com )
Created on: 7/5/2007 15:18:47
Environment: Windows XP Professional SP2 English +
Visual Studio 2005 v8.0.50727.762

Modification history:
===========================================================================

The following code compiles under MS VS 2005.

defn === definition
decl === declaration

forward decl is used when you need to know the name
of a type before the defn of that type.

If you don't have defn of a type, you can only play with the type name.
You cannot do anything that is meaningful for that type, simply because
you cannot construct an object of that type.

*/

#include <iostream>
#include <string>

using namespace std;

class B; // forward decl

class A
{
public:
void f(B& rObjB, B* pObjB, B objB); // ok --- you declare f() instead of define

/**
wrong --- you are defining g(). need to define B first.
*/
/*
void g(B& rObjB, B* pObjB, B objB)
{

}
*/

private:
//B objB; // wrong --- need to know the defn to allocate memory space for objB
B& rObjB; // reference --- ok
B* pObjB; // pointer --- ok
static B sObjB; // static --- ok

};

int main(int argc, char** argv)
{

return 0;
}