How can I make a portable executable?

Question

It's there a way to compile a c/c++ source file to output a .exe file that can be run on other processors on different computers ? I am asking this for windows platform. I know it can be done with java or c# , but it uses virtual machine.

PS: For those who said that it can be done just with virtual machines or the source cod must be compiled on every machine , i am asking if all viruses are written in java or c# and you need a vm machine to be infected or you need to compile source cod of worm on your machine to be infected ? (i am not trying to make a virus, but is a good example :) )

Answer 1

Different computers use different instruction sets, OS system calls, etc., which is why machine code is platform specific. This is why various technologies like byte code, virtual machines, etc., have been developed to allow portable executables. However, generally C/C++ compiles directly to platform-specific machine code.

So a Windows exe simply won't run on another platform without some kind of emulation layer.

However, you can make your C/C++ source code portable. This means all you need to do to make your application run on another platform is to compile it for that platform.

Answer 2

Yes, you can, but it's not necessarily a good idea.

Apple introduced the idea of a fat binary when they were migrating from the Motorola 68000 to the PowerPC chips back in the early 90s (I'm not saying they invented it, that's just the earliest incarnation I know of). That link also describes the FatELF Linux universal binaries but, given how little we hear about them, they don't seem to have taken off.

This was a single file which basically contained both the 68000 and PowerPc executables bundled into one single file and required some smarts from the operating system so it could load and execute the relevant one.

You could, if you were so inclined, write a compiler which produced a fat binary that would run on a great many platforms but:

• it would be hideously large; and
• it would almost certainly require special loaders on each target system.

Since gcc has such a huge amount of support for different platforms and cross-compiling, it would be where I would concentrate the effort, were I mad enough to try :-)