Error compiling template based class

[maverick]

Hello

I am getting an error when i am trying to instantiate an object of the
template based class

#include "foo.h"
int main()
{

CFoo<intmyFoo ;
return 1 ;
}

now I have 2 files
foo.h
---------------------------------------------------

template < class CFooTempclass CFoo
{
CFoo();
~CFoo() ;
};


foo.cpp
--------------------------------------------
#include "foo.h"

template < class CFooTemp>
CFoo<CFooTemp>::CFoo()
{

}


template < class CFooTemp>
CFoo<CFooTemp>::CFoo()
{

}


------------------------------------------------------------

I get the following errors

main.cpp:12: undefined reference to `CFoot<int>::CFoo()'

main.cpp:14: undefined reference to `CFoo<int>::~CFoo()'


However this error is not seen when i include "foo.cpp" instead of foo.h

[Victor Bazarov]

maverick wrote:

Hello

I am getting an error when i am trying to instantiate an object of the
template based class

RTFFAQ

V
--
Please remove capital 'A's when replying by e-mail
I do not respond to top-posted replies, please don't ask

[mlimber]

maverick wrote:

Hello

I am getting an error when i am trying to instantiate an object of the
template based class

#include "foo.h"
int main()
{

CFoo<intmyFoo ;
return 1 ;
}

now I have 2 files
foo.h
---------------------------------------------------

template < class CFooTempclass CFoo
{
CFoo();
~CFoo() ;
};


foo.cpp
--------------------------------------------
#include "foo.h"

template < class CFooTemp>
CFoo<CFooTemp>::CFoo()
{

}


template < class CFooTemp>
CFoo<CFooTemp>::CFoo()
{

}


------------------------------------------------------------

I get the following errors

main.cpp:12: undefined reference to `CFoot<int>::CFoo()'

main.cpp:14: undefined reference to `CFoo<int>::~CFoo()'


However this error is not seen when i include "foo.cpp" instead of foo.h

Please consult this group's FAQs:

http://www.parashift.com/c++-faq-lit...html#faq-35.12

Cheers! --M

[Martin Steen]

maverick schrieb:

>
main.cpp:12: undefined reference to `CFoot<int>::CFoo()'

main.cpp:14: undefined reference to `CFoo<int>::~CFoo()'

This is a linker error. The linker doesn't know where
the code for CFoo is.

Add the file foo.cpp to your projekt/makefile. You have
to tell the compiler what files to compile and to link.

However this error is not seen when i include "foo.cpp" instead of foo.h

Of course you can include all .cpp-files into the mainfile (main.cpp).
But this would result in long compile times and a code that is
very hard to maintain.

-Martin

[red floyd]

Martin Steen wrote:

maverick schrieb:

>>
main.cpp:12: undefined reference to `CFoot<int>::CFoo()'

main.cpp:14: undefined reference to `CFoo<int>::~CFoo()'

This is a linker error. The linker doesn't know where
the code for CFoo is.

No, Martin, it's a template instantiation issue.
http://www.parashift.com/c++-faq-lit...html#faq-35.12

[Martin Steen]

red floyd schrieb:

>
No, Martin, it's a template instantiation issue.
http://www.parashift.com/c++-faq-lit...html#faq-35.12

Ups, of course you're right. That's why it's good to have templates
in a .hpp include file.

-Martin

[Greg Comeau]

In article <11*********************@f16g2000cwb.googlegroups. com>,
maverick <ra*****@gmail.comwrote:

>I am getting an error when i am trying to instantiate an object of the
template based class

#include "foo.h"
int main()
{
CFoo<intmyFoo ;
return 1 ;
}

now I have 2 files
foo.h
---------------------------------------------------

template < class CFooTempclass CFoo
{
CFoo();
~CFoo() ;
};

foo.cpp
--------------------------------------------
#include "foo.h"

template < class CFooTemp>
CFoo<CFooTemp>::CFoo()
{
}

template < class CFooTemp>
CFoo<CFooTemp>::CFoo()
{
}

------------------------------------------------------------

I get the following errors

main.cpp:12: undefined reference to `CFoot<int>::CFoo()'
main.cpp:14: undefined reference to `CFoo<int>::~CFoo()'

However this error is not seen when i include "foo.cpp" instead of foo.h

Check out http://www.comeaucomputing.com/techt.../#whylinkerror
--
Greg Comeau / 20 years of Comeauity! Intel Mac Port now in beta!
Comeau C/C++ ONLINE == http://www.comeaucomputing.com/tryitout
World Class Compilers: Breathtaking C++, Amazing C99, Fabulous C90.
Comeau C/C++ with Dinkumware's Libraries... Have you tried it?

[red floyd]

Martin Steen wrote:

red floyd schrieb:

>>
No, Martin, it's a template instantiation issue.
http://www.parashift.com/c++-faq-lit...html#faq-35.12

Ups, of course you're right. That's why it's good to have templates
in a .hpp include file.

No biggie, we've all made oopses here. :-)

I'm sure you'll correct one of my posts next time :-)

[Greg Comeau]

In article <eh*************@news.t-online.com>,
Martin Steen <A0***************@spamgourmet.comwrote:

>maverick schrieb:

>main.cpp:12: undefined reference to `CFoot<int>::CFoo()'
main.cpp:14: undefined reference to `CFoo<int>::~CFoo()'

This is a linker error. The linker doesn't know where
the code for CFoo is.

Add the file foo.cpp to your projekt/makefile. You have
to tell the compiler what files to compile and to link.

That's insufficient because instantiation throws in some
curves over the traditional linker. See
http://www.comeaucomputing.com/techt.../#whylinkerror
--
Greg Comeau / 20 years of Comeauity! Intel Mac Port now in beta!
Comeau C/C++ ONLINE == http://www.comeaucomputing.com/tryitout
World Class Compilers: Breathtaking C++, Amazing C99, Fabulous C90.
Comeau C/C++ with Dinkumware's Libraries... Have you tried it?