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Integer values ​​at compile time

I need to write some constants in different files with some integer id. For instance:

#define MESSAGE_FIRST 0

In another file:

#define MESSAGE_ANOTHER 1

Any ways to automatically get this id at compile time? Sort of:

#define MESSAGE_AUTO GetNextId()

I can not use the enumerations here, because these directives will be in different files.

Thank.

ps GCC, Linux

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2 answers

You can make a compile-time counter with an overload of inheritance and functions:

template<unsigned int n> struct Count { bool data[n]; };
template<int n> struct Counter : public Counter<n-1> {};
template<> struct Counter<0> {};
Count<1> GetCount(Counter<1>);

#define MAX_COUNTER_NUM 64
#define COUNTER_VALUE (sizeof(GetCount(Counter<MAX_COUNTER_NUM + 1>())) / sizeof(bool))
#define INC_COUNTER Count<COUNTER_VALUE + 1> GetCount(Counter<COUNTER_VALUE + 1>);

You can see it in action here . Also works with msvc.

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, GCC. GCC (AFAIK per-file) __COUNTER__, .

, ++.

:

enum {
    FIRST = 0,
    SECOND,
    THIRD
};

, , :

#define FIRST 0
#define SECOND (1 + FIRST)
#define THIRD (1 + SECOND)
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