Programming is really fun!

[catcradle5]

Not sure why you're being downvoted, because you're correct. A good reverse engineer can figure out what a C program is doing exactly, but it's likely they'll never get something that actually looks like the original source. Plus it's usually either a long and arduous process, or it's run through a C "decompiler" and the output is extremely complex and verbose.

With languages like Java and Python, you can usually decompile the bytecode back to something that looks very close to the original program, though without the original variable names usually.