Can a C program modify its executable file?

Question

I had a little too much time on my hands and started wondering if I could write a self-modifying program. To that end, I wrote a \"Hello World\" in C, then used a hex editor

Answer 1

All present answers more or less revolve around the fact that today you cannot easily do self-modifying machine code anymore. I agree that that is basically true for today's PCs.

However, if you really want to see own self-modifying code in action, you have some possibilities available:

• Try out microcontrollers, the simpler ones do not have advanced pipelining. The cheapest and quickest choice I found is an MSP430 USB-Stick

• If an emulation is ok for you, you can run an emulator for an older non-pipelined platform.

• If you wanted self-modifying code just for the fun of it, you can have even more fun with self-destroying code (more exactly enemy-destroying) at Corewars.

• If you are willing to move from C to say a Lisp dialect, code that writes code is very natural there. I would suggest Scheme which is intentionally kept small.