How to determine the length of an array at compile

问题:

Are there macros or builtins that can return the length of arrays at compile time in GCC?

For example:

int array[10];

For which:

sizeof(array) == 40
???(array) == 10

Update0

I might just point out that doing this in C++ is trivial. One can build a template that returns the number inside []. I was certain that I'd once found a lengthof and dimof macro/builtin in the Visual C++ compiler but cannot find it anymore.

回答1:

(sizeof(array)/sizeof(array[0]))

Or as a macro

#define ARRAY_SIZE(foo) (sizeof(foo)/sizeof(foo[0]))

    int array[10];
    printf("%d %d\n", sizeof(array), ARRAY_SIZE(array));

40 10

Caution: You can apply this ARRAY_SIZE() macro to a pointer to an array and get a garbage value without any compiler warnings or errors.

回答2:

I wouldn't rely on sizeof since aligment stuff could mess up the thing.

#define COUNT 10
int array[COUNT];

And then you could use COUNT as you want.

回答3:

    sizeof(array) / sizeof(int) 

回答4:

im not aware of a builtin that does this, but i recently used:

sizeof(array)/sizeof(array[0])

to do just that