Thread: Unresoled symbol linker error

  1. #1
    Registered User
    Join Date
    Dec 2002

    Unresoled symbol linker error

    Hopefully the last major question on this project...

    I know what this error typically means - that the linker couldn't find the function definition that you used and declared. But I'm confused. I have two cpp files (driver and MemoryManager) and a header file (MemoryManager). part of driver.cpp's main():

    // previously defined simple class called MyTest
    MemoryManager::Mgr mem( MemoryManager::printall );
    MyTest* foo = mem.alloc<MyTest>();
    Now in the header file:
    class Mgr {
    	// some snippage, I think these are the relevant parts
    	template< class T > T* alloc( int = 1 );
    	pvomap allPtrs;
    And in the definition file:
    	template<class T> T* Mgr::alloc( int a ) {
    		T* ptr = new T[a];
    		allPtrs[ ptr ] += a;
    		return ptr;
    This function gets called and appears to me to be defined. Using Borland 5.5.1, I run:
    bcc32 driver.cpp MemoryManager.cpp
    It compiles correctly but generates the linker error:
    Unresolved external 'MyTest * MemoryManager::Mgr::alloc<MyTest>(int)' referenced from DRIVER.OBJ. I cannot figure out why I'm getting this - the compiler doesn't complain that I've left a member function undefined or that I've defined one that doesn't exist, and as near as I can tell the prototypes match. Can anybody see why it will not work? TIA!

  2. #2
    C++ Developer XSquared's Avatar
    Join Date
    Jun 2002
    Ontario, Canada
    Are you sure that MemoryManager.cpp is including MemoryManager.h?
    Naturally I didn't feel inspired enough to read all the links for you, since I already slaved away for long hours under a blistering sun pressing the search button after typing four whole words! - Quzah

    You. Fetch me my copy of the Wall Street Journal. You two, fight to the death - Stewie

  3. #3
    Registered User
    Join Date
    Dec 2002
    Indeed, it is.

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