Writing cross-platform C++ Code (Windows, Linux and Mac OSX)

Question

This is my first-attempt at writing anything even slightly complicated in C++, I'm attempting to build a shared library that I can interface with from Objective-C, and .NET apps (ok, that part comes later...)

The code I have is -

#ifdef TARGET_OS_MAC   // Mac Includes Here #endif  #ifdef __linux__   // Linux Includes Here   #error Can't be compiled on Linux yet #endif  #ifdef _WIN32 || _WIN64   // Windows Includes Here   #error Can't be compiled on Windows yet #endif  #include <iostream>  using namespace std;  bool probe(){   #ifdef TARGET_OS_MAC     return probe_macosx();   #endif   #ifdef __linux__     return probe_linux();   #endif   #ifdef _WIN32 || _WIN64     return probe_win();   #endif }  bool probe_win(){   // Windows Probe Code Here   return true; }  int main(){    return 1; } 

I have a compiler warning, simply untitled: In function ‘bool probe()’:untitled:29: warning: control reaches end of non-void function - but I'd also really appreciate any information or resources people could suggest for how to write this kind of code better....

Answer 1

instead of repeating yourself and writing the same #ifdef .... lines again, again, and again, you're maybe better of declaring the probe() method in a header, and providing three different source files, one for each platform. This also has the benefit that if you add a platform you do not have to modify all of your existing sources, but just add new files. Use your build system to select the appropriate source file.

Example structure:

include/probe.h src/arch/win32/probe.cpp src/arch/linux/probe.cpp src/arch/mac/probe.cpp 

The warning is because probe() doesn't return a value. In other words, none of the three #ifdefs matches.