On Wed 2003-02-12 at 00:06:24 -0800, [EMAIL PROTECTED] wrote: > Hi, > I am using the GNU gcc version 3.2 (Mandrake Linux 9.0 3.2-1mdk) to compile > the program listed below. I get the compile time error: > > 23: field `cb' has incomplete type > > Can somebody please give me a hint on why the compiler is complaining?
Because you try to use class C before it is defined (you declared it above, but the definition comes afterwards). As long as the class is only declared, you may only use it in limited context. For example, you may create a pointer or reference to the class, you may also define new types based on the class (typedef). But when you define class D, the compiler tries determine the memory layout of the class, and thefore has to know more about C than it does at that point. A more detailed explanation can be found in http://www.cuj.com/experts/2002/austern.htm?topic=experts HTH, Benjamin. [... reduced example to the relevant part ...] > class C; > > class D > { > C cb; > }; > > class C > { > int foo; > }; > > int main() { }
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