Note that the question here is about the C language itself -- obviously a physical computer is not equivalent to a Turing machine with infinite storage. But the

Note that the question here is about the C language itself -- obviously a physical computer is not equivalent to a Turing machine with infinite storage. But the issue seems to be that C fundamentally uses the idea of addressable storage -- objects have addresses, and those addresses must be a finite length (the length of a pointer), which is implementation-dependent but must be finite so that sizeof(pointer) returns a valid result. Even if you could have an infinite amount of RAM, no standard C implementation could address it. The accepted answer tries to go further with register variables (which officially don't have addresses) and recursion (whose depth is not limited by the standard), but founders on the limitation that you can't make an array out of register variables. Functions can only have a finite number of arguments and return a finite-sized structure. Another answer from a couple years later tries to make a non-addressable array using va_list and va_copy(). I don't know enough about the quirks of varargs to tell whether this would work, although nobody seems to have an unanswered objection so far.