Is it possible to define a class in 2 or more files in C ++?

Question

I know that you can implement a class in multiple files (yes, I know this is a bad idea), but I want to know if it is possible to write a class definition in separate files without getting an override error (maybe some tricks, or else ... )

Answer 1

No, not the same class, but why do you need it?

You can define two classes with the same name in the same namespace (the same signature! It will actually be the same class in general, just defined in two ways) in two different header files and compile your program if your source files do not include both headers. Your application may even be connected, but then at runtime everything will not work as you expect (it will be undefined behavior!) If the classes are not identical.

See Charles Bailey's answer for a more formal explanation.

---

EDIT:

If you want one class to be defined by more than one file in order to (for example) add automatically generated functions to your class, you could #includeadd a secondary file in the middle of your class.

/* automatically generated file - autofile.gen.h */
void f1( ) { /* ... */ }
void f2( ) { /* ... */ }
void f3( ) { /* ... */ }
/* ... */

/* your header file with your class to be expanded */
class C
{
    /* ... */
    #include "autofile.gen.h"
    /* ... */
};

Answer 2

, partial #, , :

class MyClass
{
#include "my_class_aspect1.h"
#include "my_class_aspect2.h"
#include "my_class_aspect3.h"
};

#include "my_class_aspect1.inl"
#include "my_class_aspect2.inl"
#include "my_class_aspect3.inl"

Answer 3

...

1

ClassDef1.h:

class ClassDef
{
protected:
   // blah, etc.

public:
   // more blah

-

ClassDef2.h:

public:
    // Yet more blah.
};

.

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Answer 4

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Answer 5

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Answer 6

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Answer 7

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Answer 8

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Answer 9

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Answer 10

- , . .

// header file with function declarations
class C {
public:
    void f(int foo, int bar);
    int g();
};

// this goes into a seperate file

void C::f(int foo, int bar) {
    // code ...
}

// this in yet another
void C::g() {
    // code ...
}

Answer 11

There must be a reason why you want to separate the two headers, so I assume that you really want the 2 classes to be combined together to form the components of one (third) class.