Is it possible to sort arrays using preprocessor?

Question

I have a number of very long arrays. No run-time sort is possible. It is also time consuming to sort them manually. Moreover, new elements can be added in any order later, so I would like to sort them by value using C preprocessor or maybe there is any compilers flag (GCC)?

For example:

sometype S[] = {
  {somevals, "BOB", someothervals},
  {somevals, "ALICE", someothervals},
  {somevals, "TIM", someothervals},
}

must be sorted so:

sometype S[] = {
   {somevals, "ALICE", someothervals},
   {somevals, "BOB", someothervals},
   {somevals, "TIM", someothervals},
}

---

SOLVED

Ok, here is my solution:

1. Manually copy&paste each array into a temporary file called tobesorted.c
2. Sort it by 2nd column: sort -b -i --key=2 tobesorted.c
3. Copy&paste output back into original file.

Actually, it would be nice to have some possibility to call "sort" directly from the preprocessor (I had a hope that at least GCC somehow support such features, but it seems that it doesn't).

Answer 1

Do this.

1. Put your giant array in a file.

2. Sort the file with the built-in sort

3. Write a small program to create C code from the file. A C program that writes C programs is fine. You can use Python and some of it's cool template packages to make this job simpler.

4. Compile the remaining program consisting of the sorted file transformed into C code plus the rest of your program.

Answer 2

No, it is not possible. You cannot do string operations (other than concatenation) with the preprocessor. And you can't compare strings with template metaprograming, either.

[edit] What you could do is put your datastructure in a file that is meant to be preprocessed by an external build script (e.g. the unix "sort" utility), and then modify your makefile/project so that at build time, you generate a C file with the (sorted) initialized arrays