Use typedef within struct for naming and indexing text commands

Question

I am working with a simple command line application that takes in ASCI text and interprets it as a command.

I have attempted to minimize the redundancy in this appli

Answer 1

You can use macro redefinition to achieve this. First, you create a file that simply lists your commands called commands.inc:

COMMAND(quit)
COMMAND(help)
...

Then, in your C source you can #include "commands.inc" multiple times, with different definitions of COMMAND() in effect to control how it works. For example:

struct command
{
   char *name;
   int command_idx;
};

#define COMMAND(NAME) CMD_ ## NAME,

enum command_enum {
#include "commands.inc"
};

#undef COMMAND

#define COMMAND(NAME) { #NAME, CMD_ ## NAME },

struct command commands[] =
{
#include "commands.inc"
};

#undef COMMAND

(Note that this particular example relies on a C99 improvement that allows a trailing , at the end of the lists in the enum declaration and compound initialiser - you can easily work around that in C89 by adding a dummy entry at the end).