unfamiliar syntax: class MyClass;

[cpisz]

I have seen this on the top of a few header files

class SomeClass;
What does it mean?
I would expect some sort of declaration or defintion following such as

class SomeClass
{
SomeClass();
~SomeClass();

void SomeFunc();
};

or

class SomeClass class_instance;

[Steve Pope]

<cp***@austin.r r.com> wrote:

I have seen this on the top of a few header files

class SomeClass;

What does it mean?

It's a forward declaration:

http://www.parashift.com/c++-faq-lit...html#faq-39.11

S.

[Scott McPhillips [MVP]]

cp***@austin.rr .com wrote:

I have seen this on the top of a few header files

class SomeClass;
What does it mean?

It is a "forward declaration" that tells the compiler that SomeClass is
a class name. That is enough information to compile a class declaration
that contains a pointer or reference to SomeClass.

class SomeClass;

class Other
{
SomeClass* pSome;
};

Notice that this header file can be compiled without needing to
#include "SomeClass"

This trick is needed if SomeClass contains a pointer for Other. The
forward reference lets you eliminate the circular includes.

--
Scott McPhillips [VC++ MVP]

[Phlip]

cpisz wrote:

class SomeClass; What does it mean?

http://www.google.com/search?q=forward+declarations

It means the header file knows the class's name but not its size or members.

C++ code needs to see a class's body to know its size and members. If code
only needs the name (such as to declare a reference), then a header may omit
compiling the header containing that SomeClass, and thus omits every header
that header calls.

Forward declarations become important as a program grows because they
prevent small changes to rare headers from making everything recompile for
no reason. Google "compilatio n firewall".

If you see it right above its definition, someone was being officious
without adding value.

--
Phlip
http://c2.com/cgi/wiki?ZeekLand <-- NOT a blog!!!