One or more multiply defined symbols found

Question

DebugUtil.h

#ifndef DEBUG_UTIL_H
#define DEBUG_UTIL_H

#include 

int DebugMessage(const char* message)
{
    const int MAX_CHARS = 1023;
           


        

Answer 1

This function is included into every translation unit and as a result you get multiple definitions of it - each .obj file contains its own copy. When it's time to link them all together the linker rightfully shows the above error.

You can do a few things:

1. Move the definition to a .cpp file and keep only the declaration in the header.
2. Use an anonymous namespace around the function in your header file (but realize it's a hack - you will still have multiple definitions, just no name collision).
3. Mark it as inline (although it might not always work - only if the compiler actually chooses to inline it). That's also a hack for the same reason as above.