What is the aim of making define not to have value?

[janus]

Hello All,

I saw the below in a code I was going through, however I could not make much from it. Why should one have define without values?

#define MUT_RIDX_MAINTHREAD
#define MUT_RIDX_GLOBALS

Regards, \Janus

 

[James Kuyper]

Hello All,

I saw the below in a code I was going through, however I could not make much from it. Why should one have define without values?

#define MUT_RIDX_MAINTHREAD
#define MUT_RIDX_GLOBALS

For use in statements such as

#ifdef MUT_RIDX_MAINTHREAD

or

#ifndef MUT_RIDX_GLOBALS

or

#if defined(MUT_RIDX_MAINTHREAD) && defined(MUT_RIDX_GLOBALS)