C++ Classes without class body declared outside of the namespace

Question

I'm really new to C++ Programming and I'm trying to teach it myself. While I was having a look at some code I noticed the following:

#ifndef _someclass_h_
#define _someclass_h_

class A;
class B;
class C;

namespace somenamespace{

class SomeClass 
{
public: 

...
};
}

I'm confused about the classes A, B and C being declared outside of the namespace while not having any class body. What is done here? Does it have something to do with templates?

Thanks in advance!

Search Keyword: "Forward Declaration". – user4581301 Jul 24 '17 at 18:56 — user4581301, Jul 24 '17 at 18:56

score 0 · Answer 1 · answered Jul 24 '17 at 18:58

0

These are forward declarations. C++ programmers use forward declarations to avoid having to include the header file for a class definition.

The classes A, B, and C are declared in the global namespace.

answered Jul 24 '17 at 18:58

RichS

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C++ Classes without class body declared outside of the namespace

1 Answers1