C++ function definition error (parameter passing)

Question

I'm trying to call my templated function with no success :(

My memaddr.h:

#ifndef __MEM_ADDR_WRITER__
#define __MEM_ADDR_WRITER__

#include <windows.h>
#include <tlhelp32.h>
#include <stdio.h>

namespace MemAddr {

    template <typename WRITABLE>
    int WriteMemoryAddress(const char* process, unsigned long address, WRITABLE value);

}

#endif

The call:

byte value = 0xEB;
MemAddr::WriteMemoryAddress("jamp.exe", 0x004392D2, value);

Error Message:

undefined reference to `int MemAddr::WriteMemoryAddress<unsigned char>(char const*, unsigned long, unsigned char)`

Answer: Templates needs to be defined in headers.. (@Shaggi)

Answer 1

The function template

template <typename WRITABLE>
int WriteMemoryAddress(const char* process, unsigned long address, WRITABLE value);

is not defined. Include its definition in the header file (memaddr.h):

template <typename WRITABLE>
int WriteMemoryAddress(const char* process, unsigned long address, WRITABLE value)
{
    /* do something */
}

The function template will be instantiated once when you use it.