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Undefined reference, even though all object files are included

Posted on 2004-10-29
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Last Modified: 2013-11-18
I have a template (non-member) function that is declared inside a namespace in an hpp file and defined in a cpp file. It is compiled, and the corresponding o file is sent to the linker OK. My main.cpp includes the relevant hpp file. But I still get an "undefined reference" error to the function when I try to call it from main(). I'm stumped. What could be wrong?
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Question by:loveslave
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    Accepted Solution

    by:
    Templates need to be declared and defined in the hpp file. The compiler replaces the template arguments to generate actual code it will compile then. So the cpp won't be looked at, when you use the template inside another cpp file.
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    Expert Comment

    by:jkr
    >>What could be wrong?

    The problem is that - even though the C++ standard allows separating template declarations and implementations - there's no compiler out there that supports that. So, the easiest workaround is to

    #include "template.cpp"
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    by:Sys_Prog
    As of now, the most widely approach being declaring and defining the templates functions/classes in the header file itself since most compilers do not support separating template declarations from implementation.

    Amit
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    Expert Comment

    by:Sys_Prog
    The following link provides an explanatio for the same

    http://www.cplusplus.com/doc/tutorial/tut5-1.html

    Amit
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