Mixing extern and const

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  • Yes, you can use them together.
  • And yes, it should exactly match the declaration in the translation unit it’s actually declared in. Unless of course you are participating in the Underhanded C Programming Contest 🙂

The usual pattern is:

  • file.h:
    extern const int a_global_var;
  • file.c:
    #include "file.h"
    const int a_global_var = /* some const expression */;

Edit: Incorporated legends2k’s comment. Thanks.

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